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THE CHILDREN'S LIBRARY 
OF WORK AND PLAY 

Cakpentrt and Woodwork. 
By Edwin W. Foster 

Electricity and Its Everyday Uses 
By John F. Woodhull, Ph.D. 

Gardening and Farming 

By Ellen Eddy Shaw 

Home Decoration 

By Charles FrankHn Warner, Sc.D, 

Housekeeping 

By Elizabeth Hale Oilman. 

Mechanics, Indoors and Out 
By Fred T. Hodgson. 

Needlecraft 

By Effie Archer Archer 

Outdoor Sports, and Games 

By Claude H. Miller, Ph.B. 

Outdoor Work 

By Mary Rogers Miller 

Working in Metals 

By Charles Conrad SleffeL 




Photograph bj' Underwood & Underwood 

A Motor Boat Model 

"In the making of little models of this kind, you will encounter many 

things that will tax your skill and ingenuity, as amateur workmen." 



^«* 



.-^^ 



ALL RIGHTS RESERVED, INCLtTDING THAT OF TRANSLATION 
INTO FOREIGN LANGUAGES, INCLUDING THE SCANDINAVIAN 



COPYRIGHT, I9II, BY DOUBLEDAY, PAGE & COMPANY 






ACKNOWLEDGMENT 

The publishers wish to acknowledge their in- 
debtedness to the Horace Mann School for their 
courtesy in permitting certain of the photographs 
to be taken for this volume. 



I 



CONTENTS 

PART I 



I. A Pathway of Cement 3 

Purchasing property. River Passaic — Removing rocks 
and other obstacles — Preparing for cement sidewalk — 
Digging trench and purchasing materials — Making, laying, 
and properly placing concrete — The lever and roller and 
application — Moving heavy bodies with lever and roller — 
Finishing the cement sidewalk — How to make good con- 
crete walks. 

II. Building a Boat-house 36 

Qualities of the inclined plane — Dismantling an old 
barn and out-houses — Blocks and tackle, ropes and pulleys — 
Strength and care of ropes — Building a boat-house, using 
old materials — Strength of timber floors — Method of 
construction — Holding power of nails — Doors and windows 
for boat-house — The use of rollers in moving heavy weights 

— Sliding ways for boat — How heavy stones were raised to 
tops of Egyptian Pyramids. 

III. Bridge and Boat Work 65 

Dimensions of the launch — Arrival of The Mocking- 
Bird — An interesting boat talk — A sail on the river — 
Building a small foot-bridge — The same completed — Some 
rules for sailing a launch — Fitting up boat-house and dock 

— Preparing block for keel — The winch and its construction 

— The wheel and axle as a mechanical power — The fusee, 
and what it means — Some problems solved. 

IV. Making a Gasolene Launch 84 

Arrival of boat material — Laying keel and keelson — 
Setting up the boat and giving her shape — Laying engine 
bed — Installing engine and propeller — Nailing on planking 
— Table of offsets — Gasolene engine and carburetor — 
Dimensions of engine and propeller — Gas engines, generally 

— Danger of using gasolene — The proper use of yacht flags 
for signalling. 



CONTENTS 



V. A Talk About Engines 110 

Water around the cylinder — The carburetor and spark 
coil — Running the engine in boat-house — Varnishing the 
boat — A steamboat on the river — A story of the first 
steam engine — How the steam acted in the case — The slide 
valve, piston and steam chest — Internal and external 
engine heaters — Horsepower and how calculated — Foot 
pounds, dry steam and condensation — Expansion of gases, 
turbines — Gilding the name — Constructing picnic tables 
and seats — Height of tables, chairs and benches. 

VI. Propeller and Other Screws 136 

The launch of the Caroline — Trial of the new boat — 
Description of the screw as a power — The wheel and worm 
and endless screw — Formula for counting power of wheel 
and worm screws of various kinds — Archimedian screw and 
water lifter — Some data of power of "wheel and worm" 
— The screw propeller, with data — How to calculate force 
of propeller screws — Finding pitch and other lines for pro- 
peller — The screw auger or boring tool — Adhesion of 
ordinary wood screws — How to loosen and withdraw rusty 



VII. Aeroplanes 158 

Seats for riverside — Model aeroplane for the "Fourth" — 
Dimension on construction of planes — Why a monoplane 
rises from the earth — The gyroscope as a balancer — The 
biplane and its construction — Aeroplanes generally — 
The French aeroplane "Demoiselle" — How to make a 
model aeroplane — Illustrations and details of model 
aeroplane — Some general remarks. 

VIII. Kites, Sundials, Patents 185 

The theory of kite-flying — The highest kite ascent — 
The flat plane kite — The kite a small aeroplane — A box 
kite of common type — Cellular kites of various kinds — 
Pairs and bevies of kites — Bird flight and motion — War 
kites of various kinds — Wind gauges and wind force — 
Patents and how to secure them — A simple sundial — 
How to make an oval flower bed. 

IX. Tides 212 

The "why" of the tides explained — Globular form of 
the earth proved — Day and night — Phases of the moon — 
Attraction of the sun and moon — Newton's theory of the 
tides — Height of tides — A simple hygrometer — The 
Australian boomerang — Theory of the pump. 



CONTENTS 



X. Wall Making and Plumbing 237 

Protecting the river bank — Concrete retaining walls — 
Big dams in the West — Galveston sea wall — The great 
dam across the Nile — Proposed irrigation works in Babylon 
— Some properties of light and sound — Hints on amateur 
plumbing — The peppermint test — Barometers of various 
kinds — Thermometers, and their uses — Something about 
steel springs — How to make a cross-bow — The gyroscope 
and its uses. 

PART II 
I. Some Practical Advice 271 

The inventor, ancient and modern — Barriers to mechanical 
progress in the past — Laws of gravitation — How to ad- 
just sewing machines. 

II. Mechanical Movements 306 

Coffee mills — Pulleys — Pumps — Pistons — Levers — 
Steam engine and water wheel governors, etc. 

III. The Weather and Indoor Work .... 349 

How to make a rain gauge — Hail — Snow — Designing, 
making and inflating paper balloons — Magnetized 
watches — A boy's wheelbarrow — Vacuum cleaners. 

IV. Motors and Typewriters . . . . . . 387 

Motors, gasolene and steam — Automobile frames — The 
modern typewriter — Directions for securing copyrights. 



ILLUSTRATIONS 



A Motor-Boat Model 


• 


Frontispiece ^ 


FACING PAGE 


Boat-House and Work-Shop 42 ^ 


The Creek .... 








70^ 


Making a Motor Launch 








88 ^ 


Finishing the Motor Launch 








112 - 


The Monoplane Model Complete 








160 - 


Making an Aeroplane Model 








180 - 


Making Xites 








190 


A Sundial Made of Concrete 




1 




208 - 



H 



PART I 



A PATHWAY OF CEMENT 

I DO wish papa would buy the land from Mr. 
Breigel. The weather will soon be fine enough 
to play out of doors!" 

So said Jessie Gregg, a rosy-cheeked girl of twelve, 
to her eldest brother, Fred, one evening in March, 
as they stood in the porch way of their home, situated 
near the bank of the Passaic River, a few miles from 
the city in which Mr. Gregg had his business offices. 

**Why, Jessie," said Fred, ''papa told me this 
morning, at breakfast, he expected to close the 
deal, that is, get the deed of the property, this 
afternoon. I am just as anxious as you are to have 
the matter settled, for if he gets the land, I will 
have a lot of work to do, and I want to commence 
it right away. The land must be ours, for papa is 
later than usual this evening. Oh! there's the train 
just coming in; he will be here in a few minutes, 
and then we'll know." 

**0h, Fred! he and George are coming now. I 
see them at the turn of the road. I'll run to meet 

3 



4 MECHANICS 

them." Away she scampered, and almost upset 
her father by jumping into his arms, as she was 
quite a plump, husky girl and evidently a pet, 
for her father kissed her fervently as she slid from 
his arms to the ground. Then the three trudged 
homeward. 

"Jessie," said George, a younger brother, "I 
have a secret for you if you won't tell Fred, until 
papa has told him. 

"What is it?" 

"Papa has bought the land, and has got it in his 
pocket." 

"Oh! I am so glad," said Jessie, "but how can he 
have it in his pocket." 

"George means that I have there the ^papers, 
deeds, conveyances, and receipts, giving me the 
sole ownership of the land, and all that is on it, 
including the trees, old barn, and other structures; 
so, girlie, you can get down to the river now 
without having to climb a fence." 

Fred met his father on his arrival at the house, 
but was too well behaved to ask him about the land, 
though he was as anxious to know as he could be. 
His father saw the boy's anxiety and after tea asked 
him to go with him into his den, a little room nicely 
fixed up some time previous, containing many 



A PATHWAY OF CEMENT 5 

articles of wood, brass, and plaster of Paris, Fred 
and George had made during the past winter. 
Jessie, also, had contributed many little things to- 
ward the decoration of "the lion's den," as 
she called the room into which her father retired 
to have his evening smoke, to take a friend, or to 
do a little private business. 

When seated, Mr. Gregg called Fred to his desk, 
and talked over some home affairs before < he said: 
"Now, my boy, since I have secured the property 
behind us, as you children desired, I shall expect 
you and George to help by your labour, and by the 
knowledge you obtained at the training school, 
in making the improvements on the land and the 
water front we have talked of so often. I am sure, 
with my advice and assistance, you will be able 
to do most of the work, or at least to superintend 
it in such a way that the labour and expenditure 
will not be wasted. You know, Fred, I am not a 
rich man, so cannot afford to waste money on ex- 
periments." 

"Indeed, father," said Fred, "I will do all I can. 
You may count on my giving my best attention to 
whatever work and improvements you entrust me 
with." 

"That is well said, my boy, and what I expected 



6 MECHANICS 

from you. We will begin operations by putting 
down a cement pathway from the walk now leading 
to the house from the street, and continue it to the 
river, where you must build a small boat 
house and workshop, as I intend either to 
purchase a small gasoline launch for our own 
use, or have you build one, if you feel equal 
to that/' 

" Oh ! father, you are so good," said Fred. "There 
is nothing I'd like better than to do this work, 
and particularly to build a boat. I'm sure I can 
do that with your help and advice. As to putting 
down the pathway, that I can do very well, after my 
good training in cement works." 

"All right, my son. We'll see in the morning 
what old material we have on the two places which 
can be used. There must be quite a quantity of 
lumber, timber, bricks, hard mortar, and plaster 
in and about the old barn and the smaller buildings." 

The next morning George evidently had something 
on his mind, and seemed to be on the point of 
explosion. Mrs. Gregg noticed this and said to 
him, "Why are you so restless this morning? Why 
don't you finish your breakfast?" 

"Oh! mother," he exclaimed, "I am too glad. 
I am so full of the good things Fred told me last 



A PATHWAY OF CEMENT 7 

night and this morning I haven't any room for 
breakfast." 

**What did Fred say to you?" asked the mother. 

*'0h! he told me he was going to build a cement 
walk right from the door here to the river, and do 
lots of other things; and best of all, mother, he is 
going to build a boat, a real boat, that will be driven 
by a gasoline engine, just like Walter Scott's. 
That will be glorious! I can take you and Jessie 
up the river to Belville to see aunty, whenever you 
want to go." 

"Very well, George; we will see about that after 
the boat is ready to take on passengers." 

Breakfast over, the whole family walked out to 
see the newly acquired property. They had all 
seen and walked over the grounds often, but never 
before with that feeling of pride in ownership 
which possession creates. 

As there could be no objection to the removal 
of the line fence between the newly acquired property 
and the homestead, Fred got a handsaw, and cut 
down a part of it, making an opening some nine or 
ten feet wide, so that all could pass into the new 
place without climbing or stumbling. 

The old barn was the first thing examined, and 
it was found to be in a state of good preserv^tioUj 



8 MECHANICS 

and quite large. It had been built — perhaps in 
Colonial times — of heavy timb^er, oak, chestnut, 
and pine, and it contained enough timber and lum- 
ber to build two or three small cottages. There 
was a big pile of broken bricks and mortar lying 
against one side of the barn; and another large pile 
of bowlders, or field stones, near the fence. ''These," 
Fred said, "will be fine to build a little landing 
place or pier for the boat. The broken bricks and 
hard mortar will make grand stuff for the founda- 
tion of the cement pathway." 

There were also two or three small buildings 
on the place. One had been used for a poultry 
house, another for a tool house, and a third seemed 
to have been a sort of cattle shed. Mr. Gregg 
suggested their removal, of which all approved. . 

There were quite a number of good-sized trees 
on the grounds, and these rendered it a little diffi- 
cult to set out a straight line to the river for the 
cement walk, without cutting down several, which 
could not be considered. There was one direc- 
tion, however, that would admit of a walk, about 
four feet wide, but there were some big rocks or 
bowlders in the way, that would have to be removed 
before a straight path could be made. Still it was 
decided to put it there. 



A PATHWAY OF CEMENT 9 

"The rocks," said the father, "can be removed 
by blasting, by lifting them out of their beds and 
rolling them aside, or moving them down to the 
river, where they will form a good protection against 
both current and ice." 

"I think they can be moved," said Fred, "if I 
can get levers and rollers; and they will make 
fine breakwater stones." 

Jessie found two suitable trees, upon which 
Fred promised to put up a strong rope swing, as 
soon as the place could be cleaned up and made tidy. 

"Now, Fred," said the father, "this cement walk 
should be commenced at once, so that it will be dry 
and hard before you go on with other work. I 
will employ a labouring man to help you, one who 
will do the heavy work, as I do not want you to 
over-exert yourself. You have a number of tools 
now in the shed, and, when I come home from the 
office this evening, we will make out a list of the 
other tools and materials you will require to finish 
the intended work. In the meantime you and 
George can be making a number of wooden stakes, 
about eighteen inches long and two inches square. 
Point them sharply at one end so that they may be 
driven into the ground their whole length. You 
will require thirty or forty of these. After getting 



10 MECHANICS 

them, take a clothes line, old halyard, or any rope 
or heavy string your mother can find for you, and 
stretch it from the house down to the river, at the 
point we decided upon. Drive in a stake near the 
river, tie one end of the rope to it, pull tightly, and 
stretch the rope from the river to the house. It 
will then show you where one edge of the walk is 
to be. After that is done, get another rope or string 
and, starting from the house end of the walk, measure 
off four feet for the proposed width. Drive in a 
stake at that point, and tie one end of the second 
rope to it; then go toward the river with the other 
end, making the rope extend the whole length of 
the path and drive in another stake which must 
be four feet from the first rope. To this stake tie 
the end of the rope and make it tight. Be sure to 
have the two ropes exactly four feet apart at each 
end, as well as along the whole length. You will 
find it to your advantage to get a straight strip of 
wood, say, one or two inches thick both ways, and 
cut it exactly four feet long. It can then be used as 
a measuring stick or gauge, for the distance between 
the ropes, which is to be the width of the walk, 
and by using it you will have a parallel and uniform 
path from start to finish." 

Mr, Gregg had passed an examination in the 



A PATHWAY OF CEMENT 11 

Massachusetts School of Technology, and had won 
a position as civil engineer in New York which 
later he abandoned for the profession of law; hence 
his knowledge of practical mechanics and engineering. 
After Jessie and George had gone to school, 
Fred started on his new undertaking ' with enthusi- 
asm. He found quite a number of pieces of wood, 
out of which he made over forty stakes, and pointed 
them nicely with the large hatchet he always kept 
sharp and in good order. By tying several pieces 
together, it did not take him long to find cord enough 
to set out the whole walk. An old halyard that 
had been taken from the flag pole and replaced by 
a new one answered the purpose admirably. Driv- 
ing a stake into the ground, near the house, he tied 
one end of his cord to that, and stretched it down 
to the river bank to the point chosen for the end 
of the walk, where another stake was driven in and 
the cord tied to it. The long stretch between the 
two stakes would not allow the cord to be tight 
enough to make a straight line between the two 
points, but Fred left it as it was, to be adjusted 
when his father came. With his rod he measured off 
four feet from the first stake, across the intended 
path, and drove in another stake to which he at- 
tached another cord. Then going down to the river 



12 MECHANICS 

he measured off the width of the walk from the long 
cord, and drove in another stake. He was now 
ready to have his father examine the work he had 
done, and to make suggestions or changes if such 
were deemed necessary. 

Jessie and George arrived home from school, 
having run most the the way, "to help Fred make 
the walk," and were quite disappointed to be told 
there was nothing they could do until the work was 
further advanced. 

*' We might, perhaps, commence taking down the 
old buildings," said Fred, ''and pile the lumber 
where it will be snug and dry." 

''All right," said George; so the three of them went 
over to the poultry house and Fred began by taking 
out the two or three small windows, and removing 
the doors by unscrewing the hinges. George's 
desire to pull, tear, and smash the old material was 
held in check by Fred, who advised him to be care- 
ful, and not break or destroy anything that could 
be used. After the doors had been taken off 
and laid nicely away — "to be used on the boat 
house" — and the windows and frames placed in 
a dry spot, Fred began to remove the old siding, 
or clapboards. He found this a rather difficult 
job, as they were nailed on with old-fashioned 



A PATHWAY OF CEMENT 13 

wrought-iron nails which could not readily be drawn, 
and, in trying to get the boards loose, the ends kept 
breaking and splitting; so he stopped, went inside 
the building, and took off the lining there; this also 
was a little difficult to do, but, as the boards were 
an inch thick, he did not split many of them. 

He then sawed oflf the boards alongside the 
studs, on the corners, and at the doorways to re- 
lieve the siding at the ends, and give him a good 
chance to wedge oflf the boards wherever they were 
nailed. With the help of George, he succeeded in 
getting most of them loose without serious damage. 
OF^course, he had to begin tearing the boards off 
at the top of the wall, as they lapped over each 
other like the scales of a fish. 

Mr. Gregg arrived, went over the ground, and was 
well pleased with the results of Fred's day's work. 
He assisted in straightening the long cords, and 
made a number of suggestions for the boys to follow. 
He had a strong-looking man with him, who he 
told Fred was to help him. He was an Italian, 
named Nicolo, called "Nick" for short, a kindly 
fellow, who could speak English fairly, for he had 
been employed in Newark, as a handy labouring 
man for years. He, Fred, and George soon became 
good companions, and even Jessie, though a little 



14 



MECHANICS 



shy at first, soon ibecame quite friendly toward 
him. When it was explained what was wanted 
of him, he was quite satisfied, and agreed to begin 
work in the morning. 

Next day Fred and George were at work before 
their father was out, and soon Nick arrived, bring- 
ing a spade, a crowbar, and a pick. He was im- 
mediately set to work by Fred, digging a shallow 
trench for the pathway, a little over four feet wide 
and about eight inches deep. The stretched cord 
and the four-foot rod were the guides. 




Fig. 1. Section of sidewalk 

There were a number of rocks to be removed from 
the trench, one of them near the river bank weigh- 
ing over a ton. These were left to be removed 
later. Their father, on coming out, was glad to 
see them all at work; he showed Fred and Nick 
how to prepare the edges of the trench by putting 
planks along them, as shown in Fig. 1. The boards, 
about twelve inches wide, and from twelve to six- 
teen feet long, had been taken from the old barn. 



A PATHWAY OF CEMENT 15 

After breakfast Fred worked along with his man, 
and got the trench well cleaned out, except for a 
few of the larger rocks. The smaller bowlders were 
wheeled down to the river and rolled over the 
bank to the water's edge. Near one side of the walk 
grew a large tree, whose main root ran under the 
proposed path. Mr. Gregg had noticed this in the 
morning and had told Fred to see that the root was 
cut oflf close to the line on both sides and pulled 
out altogether. '' If it isn't cut oflf, it will grow larger, 
lift up the cement flags, and perhaps break them." 
Fred saw the force of this, so had the root cut oflf 
and taken out. The operation would not kill 
the tree, though it might do it some injury. 

Now came the process of taking out the big stones, 
and a lever, ten or twelve feet long, was brought 
from the barn, in the shape of a red cedar pole, 
five or six inches in diameter at the larger end. 
Nick took an axe and chopped the big end a little 
flat on two sides, so that it could be shoved under 
the stone. A flat plank was next laid behind the 
stone on the ground, on which a fulcrum was to be 
placed, in order to get what is termed by workmen 
a "purchase." On the side of the stone next to 
the river, three planks taken from the floor of the 
barn were laid down flat at the bottom of the 



16 MECHANICS 

trench. Three other planks were laid on the top 
of the first layer, thus making a bed in the trench, 
two planks in thickness, on which the big stone was 
to be rolled. A fulcrum, consisting of an old fence 
post, was laid upon the plank, and forced up as 
close to the stone as possible. Everything was 
now ready for lifting the bowlder out of the bed, 
where it had lain perhaps for thousands of years. : 

As had been arranged, the work at this stage 
was suspended, and other work gone on with, until 
Mr. Gregg made his appearance. Upon his arrival 
all hands went to the stone, Jessie included. Hav- 
ing approved what had been done, the father sug- 
gested that rollers be placed between the two 
thicknesses of plank to increase the ease of moving 
the stone to the river when it was started. Fred 
and Nick went to the barn, and among a big pile 
of old planks, boards, and timber found eight or 
ten old fence posts, six or eight inches in diameter, 
and long enough to make two rollers, each three 
feet long, when cut in two. These were quickly 
stripped of bark by George and Jessie, while Nick 
and Fred, with axe and hatchet, soon had a number 
of them round enough to serve as rollers. The 
father then directed that the ends nearest the river, 
of the top layer of planks, be raised up, and one 



A PATHWAY OF CEMENT 17 

of the rollers placed between the two layers of 
plank near the stone, while the ends of planks nearest 
the stone should be left resting on the bottom ones. 
Another roller was placed nearer the river end of 
the planks, and all was made, as shown at Fig. 2 
— where fulcrum, lever, stone, planks, and rollers 
may be seen. 




Reac/y to turn over 



Fig, 2. Raising rock with lever 

All was now ready; the lever was adjusted in 
place under the stone and on the fulcrum. Mr. 
Gregg, Nick, and the children were gathered about 
the lever, each one pushing down, and the stone 
began to move, as the top end of the lever came 
down, much to the delight of Jessie and George, 
who kept shouting, ''There she goes! Up she 
goes!" Finally the great stone turned over on the 
plank, and was moved to near the centre. Now 
came the labour of getting the monster down to 
the bank. This was made easier by raising the 
ends of the upper planks under the stone and 



18 MECHANICS 

inserting another roller, five or six feet from the 
end. The planks holding the stone were now rest- 
ing on rollers, as seen in Fig. 3, and it was found 
easy to move, but in order to get it to the bank of 
the river the "runway," or lower planks, had to be 
laid down that distance; this would take too many 
planks, so it was decided to lay only a second length 




Reac(y io start 



Fig. 3. Moving rock on rollers 

on the ground, and then when the load had travelled 
to this length, the plank behind the stone should be 
carried forward and laid down again. This was 
continued until the load was slid into the water. 
Mr. Gregg called the children and told them to 
push against the stone, and they all were filled with 
wonder to see this great stone move along so easily 
on the rollers. 

Fred and Nick got more rollers to put between 
the planks as the stone was pushed forward, for, 



A PATHWAY OF CEMENT 19 

of course, these were continually coming out at the 
rear end of the loaded planks. The rollers had also 
to be watched and kept square across the plank 
or they would slide, making it hard to move the load. 

When the river bank was reached, Fred and Nick 
made a rough slide of old timber down to its side 
from the trench. Getting the lever properly ad- 
justed under the planks and stone, the latter was 
turned over on the slide, when it plunged into the 
river with a great splash, causing the water to fly 
and sprinkle each one of the workers, much to the 
delight of George, who thought it fine fun to see his 
father, Fred, and Nick get a wetting. 

It was decided that the stone as it lay in the 
water should form the end of the pier for the boat, 
as it was nicely situated and the proper distance 
out, being about a foot out of the water at high tide. 
The other stones were easily removed from the trench 
by Fred and his man, and were either rolled or 
wheeled down to the river, where Nick built them 
as well as he could on both sides of the big rock, 
leaving a hollow space between the walls, to be filled 
in afterward with small stones, mortar, and broken 
bricks, for the making of a good, strong boat pier. 

Mr. Gregg then took out his note -book and 
pencil, and figured out the quantity of cement. 



20 MECHANICS 

sand, and gravel required to complete the cement 
work. He found there was good sand, clean and 
sharp, on one corner of the new lot. A big pile of 
gravel and broken stones out on the street had been left 
over from the building of a two-story concrete house 
nearby, so he concluded to buy it, if not too dear. 
Measuring the trench, he found it to be 300 feet 
long, by 4 feet wide, making a surface of 1,200 feet 
to be laid with cement, concrete, and gravel, or 
broken stones. He calculated that every 100 super- 
ficial feet of the concrete walk would require about 
a barrel and a third of Portland cement; and that 
the top dressing of cement and sand, or fine crushed 
stone, required another third of a barrel; which 
totaled up to 20 barrels, all told. The concrete 
to be used was to be proportioned as follows : One 
part of cement, two parts of good, clean sand, and 
five parts of gravel, or broken stones, which should 
be small enough to pass through a ring having a 
diameter of not more than two inches. This mass 
should be well mixed, dry, on a wooden floor or mov- 
able platform, and then wetted just enough to have 
stones, sand, and cement, well moistened. All should 
be again mixed before being placed in the trench, 
and it should not be thrown in place, but shovelled 
in gently. 



A PATHWAY OF CEMENT 21 

Mr. Gregg ordered the cement by telephone, 
to be delivered at once, either in barrels or bags; 
and he got into communication with the owner of 
the gravel, and bought the whole pile. He then 
engaged a team of horses, wagon, and driver, to 
commence work the next day. By this time Nick 
had gone home, and the children came rushing into 
the house, anxious to tell their mother all the work 
they had done that day. 

The keen appetites of the younger folks gave 
positive proof of their having earned their supper, 
by actual work, and, when the meal was over, the 
father invited Jessie and the boys into his little room. 
George was asked to take with him his portable 
blackboard, some chalk, and a ruler, and all marched 
into their father's den. 

*'Now," said Mr. Gregg, "I have often told you 
I would explain to you some things about the 
mechanical powers, and this seems to be the most 
appropriate time to begin, as you have fresh in your 
minds the application of the lever as we used it 
to-day in raising and moving the big rock. I 
am glad to see that Fred grasped the idea so readily, 
for that encourages me to let him use his own judg- 
ment while doing this job. 

"The lever is known to accomplished mechanics, 



22 MECHANICS 

as *the first mechanical power', and Archimedes said 
of it, if he only had one long and strong enough, 
together with a suitable fulcrum, he could, alone, 
lift the earth from its place. 

"This Archimedes was a celebrated Greek phi- 
losopher and mathematician, who lived from about 
287 to 212 B. C. The discovery of the law of 
specific gravity, which I will some day tell you about, 
is attributed to him. I think George can tell you 
something about this great man, as I saw him and 
Jessie the other day reading Plutarch's 'Lives,' 
in which he is mentioned. 

"A lever may be formed of any strong, stiff 
material, wood, iron, steel, or similar stuff, and it 
may be of any length, or dimensions, according 
to the purpose for which it is to be used. In theory, 
it is supposed to have no weight, and is simply 
figured as a straight line having neither breadth 
nor thickness. In practice, however, a lever may be 
a handspike, a pry, a crowbar, a fire poker, a wind- 
lass bar, or any other appliance or instrument that 
can be used for prying. While we may not 
know the proper name of the little steel tool the 
dentist employs when preparing one's teeth to 
receive the filling, by cleaning out the cavities, 
we are safe in calling it a small lever. When your 



A PATHWAY OF CEMENT 23 

mother stirs the fire in the grate, she makes a lever 
of the poker, and bars of the fireplace become 
fulcrums. The fulcrum is the fixed point on which 
the lever rests when in use. The force applied is 
called the power and the object to be acted upon 
is called the weight. The spaces from the power 
and the weight, respectively, to the fulcrum, are 
called the arms of the lever. There are three 
different ways of using the lever, according to the 
relative positions of power, weight, and fulcrum. 
This rough sketch I am drawing on the black- 
board (Fig. 4) shows the lever being used to raise 




Fig. 4. Principle of lever and fulcrum 

one end of a heavy stone. Suppose W is a big 
rock, C will be the fulcrum, B the end of the lever 
under the stone, and O the power. The weight 
thrown on the lever by the man at O, raises the stone 
so that it can be blocked up, the lever and fulcrum 
arranged for another lift, and the process repeated. 
This can be continued until the stone is raised to 



24 MECHANICS 

the height required, or until it is turned over. 
This method appHes to the raising of any sort of 
weight, engine, boiler, heater, etc. 

**In this sketch the distance from B to C shows 
the short arm of the lever, and the distance from 
C to O shows the length of the long arm. 

"'A lever, used in this way, is called a lever of the 
first kind, because of its simplicity and easy adap- 
tation to many purposes. I saw George digging in 
the garden the other day, making a flower bed for 
his mother. The spade he used formed an excellent 
lever. He forced it into the ground to its full 
depth, pried the handle toward him, and broke 
loose the soil, after which he turned over the earth 
in the bed. Now, in this case, the top of the blade 
or foot-plate of the spade, rested on the hard ground, 
A* B c which was the fulcrum; the 

soil dug up was the weight. 



X 



® © and George's hand at the 

Fig. 5. Lev^erasamechanical ^^^ ^f ^j^^ gp^^^ handle, 

furnished the power. I am sure you all under- 
stand the working of a lever of this kind, but I will 
give you another illustration. 

"Here's another sketch (Fig. 5), in which A,B,C, 
together show the lever, also the power A, the 
fulcrum B, and the weight C. If I should place the 



A PATHWAY OF CEMENT 25 

fulcrum B so that it would be in the middle between 
the ends A C, there would be what is termed an 
equilibrium between the weight and the power, and 
if they are equal there will be a perfect balance 
maintained. It is on this principle that scales for 
druggists are made, the lever being suspended in 
the centre of its length, as I show in the sketch 
(Fig. 6). These scales 
are very nicely ad- 
justed, and the chains 
and receivers are made 
as nearly alike in 
weight as possible. 
The arms of the lever 
being of equal length 
from the centre, or 
pivot, permit the lever 
to stand in a perfectly 
horizontal position, unless disturbed by having a 
weight placed in either one or other of the receivers. 
In this case, the pivoted point P is the fulcrum, 
and the two points O and X may be taken as the 
power and the weight. If one pound is placed in 
the receiver at O, it will tip the scale down, and that 
will become the weight, while any commodity placed 
in the receiver at X, until the lever is again brought 




Fig. 6. Double lever as scales 



26 MECHANICS 

level, or horizontal, may be called the power. As 
another illustration I'll tell you of something that 
took place the other day. In the vacant lot are 
several piles of bricks, stones, and planks. George, 
seeing this, took one of the planks and threw it 
across several others, making a *Teeter Tauter,' 
or, as some children call it, a 'Seesaw.' He balanced 
the plank nicely, and then invited Jessie and her 
cousin to sit on it, one at each end. The two girls 
were about the same weight, and George held the 
plank until both were seated. It remained level 
and balanced, until George got on the top of it, and 
stood on the centre of its length, placing his feet 
so that one was on one side of the centre, or fulcrum, 
and the other on the other. By causing his weight 
to rest on his right foot, the right end of the plank 
would dip downward; then by throwing his weight 
on his left foot, the movement of the plank would 
be reversed, and the motion continued until George 
ceased to exert any extra pressure on either of his 
feet. What do you call the boy or girl who stands 
on the plank .?^" 

*' Sometimes," said Jessie ''we call him a 'candle- 
stick' and sometimes 'the balancer'." 

"This teeter tauter and the explanation of the 
druggist scales," said the father, "show you that 



A PATHWAY OF CEMENT 27 

many of our conveniences are due to the lever 
in one way or another. These are but a few of the 
thousands of instances I could name. Take a 
nut-cracker, for instance. There we have a sort of 
double lever, the joint being the fulcrum, the nut 
the weight, and the two handles the combined 
power or lever. By pressing the handles or levers, 
we crack the nut or overcome the weight, by crush- 
ing it. We owe many of our amusements to the 
lever in one form or another. Even our pianos 
would be impossible were it not for the combination 
of levers in the adjustment of the keys. Machinery 
and all kinds of moving instruments, including 
watches, clocks, and other fine mechanism, could 
not be perfected without the lever. The common 
every-day wheelbarrow is a good illustration of 
the use of the lever combined with the wheel. 
George fills up his barrow with stones or other 
materials that weigh two or three times the amount 
he could lift easily. Yet he gets away with the 
load, apparently with very little trouble. The 
handles form the lever or power, the wheel the ful- 
crum, and the stones the weight. George raises 
the handles, and throws the greater part of the 
weight on the fulcrum, which is the wheel, and this 
latter, acting as a roller, is easily moved around 



28 MECHANICS 

its own axle, thus enabling George to move his three- 
fold load with ease. 

"This example shows you how, by a simple 
combination of mechanical devices, labour may be 
reduced. The roller is related to the wheel and 
axle class — another of the mechanical powers. 

"In your bicycles you have a fine illustration of 
the application of the roller principle, in the ball- 
bearings. The little round balls, over which the 
axle of the wheel runs, are simply rollers rounded 
in every direction, and placed there to destroy 
friction, which they do almost entirely. 

"Another excellent illustration of the use of the 
roller is seen in the hanging of the grindstone we have 
in our back shed. The axle passing through the stone 
rests on two pairs of wheels or rollers, one pair at each 
side of the stone. If you turn the stone on its axis, 
you will notice the wheels turn also, and the effort 
required to turn the stone is hardly noticeable. 
If the grindstone were well balanced and true, and 
the little wheels the same, so that they could be 
run without friction on their bearings, the stone, 
by giving it one good turn with the hand, would 
keep revolving a very long time. So you see how 
much we are indebted to the mechanical powers 
for our present state of civilization." 



A PATHWAY OF CEMENT 29 

Next morning being Saturday, George was up 

early, put on a pair of overalls his mother had 

bought, and, when breakfast was over, all but the 

mother went out to the new property. They found 

Nick helping a teamster to unload gravel, also a 

load of cement, which was placed in a dry and 

convenient place, for once damp or wet in the least 

it becomes of little use, unless worked up immediately. 

George was full of glee. He got his wheelbarrow 

and wanted to commence work without delay. 

The father took Fred and Nick to the trench and 

explained what was to be done and the way to do 

it. "The trench is now eight inches deep," he said, 

"and you must wheel gravel, broken bricks, hard 

mortar, or cinders into it so that there will be about 

five inches of it in the trench from one end to the 

other. Put all the larger stones at the bottom, 

but before throwing in any, tamp or pound the 

ground at the bottom of the trench until it is solid 

and hard, making a good bottom for the stones to 

rest on, and ensuring the walk from settling or 

sinking in spots. 'Where the big root and rocks 

are taken out, the holes must be filled up level, 

and tamped solid. Rake off the largest of the 

gravel, and let George wheel as much of it as he 

can, and dump it in the trench, while Nick or you 



30 MECHANICS 

wheel in the balance. Finish the top of the gravel 
off with smaller sized stones, and after you have 
filled in about five inches, throw water on the whole 
with the garden hose until quite wet, and then pound 
the gravel down until it is compact and firm. This bed 
forms a good foundation for the concrete which must 
belaid on it about four inches thick, and well tamped. 
"After you have raked off the larger gravel, 
take a wire sieve, with meshes not larger than four 
to the inch, and sift the finer gravel out, to save 
for the top finish. Before filling in the concrete, 
strips of wood having straight edges on top must 
be nailed to the stakes on both sides of the walk, 
as I showed you on the blackboard in Fig. 1, marked 
A A. These strips must be placed at proper grade 
in their length, and level across from one to the 
other. A straight edge made of wood, and long 
enough to reach over the walk, and the strips as 
well, must be provided, and it may be notched out 
as I show at X, in Fig. 1. This straight edge is to 
be used in levelling off the top or finishing coat, by 
keeping both ends on the strips A A, and moving 
it along lengthwise of the walk. If the top of the 
walk is to be below the edges of the strips, you may 
notch the ends, as shown, to suit whatever depth 
may be required." 



A PATHWAY OF CEMENT 31 

Fred told his father he thoroughly understood 
the process as far as explained, and the latter then 
left. By this time Nick and George — and, we 
might add, Jessie — had wheeled into the trench 
quite a lot of gravel, but for the want of a proper 
"tamper" they had to stop. So Fred cut two pieces 
oflF a fence post, each about a foot long, and with 
an auger or boring tool, made a hole in the centre 
of the end of each, about eight inches deep, into 
which he inserted a round wooden handle, about 
three feet long. These made excellent "tampers," 
not too heavy for George to use. Jessie, persuaded 
Fred to make her "just a little one," but he told 
her not to use it much or her hands would get sore 
and too stiff to practise her music. 

The strips for the stakes were prepared, nailed on, 
and properly adjusted, and then it was time to com- 
mence the real work. Nick had nailed some boards 
on three pieces of scantling about six feet long, 
which made a good mixing table for the concrete. 
This was carried up near the top end of the walk, 
and placed where it would be handy. A pailful 
of cement was put on the board, next two pailfuls 
of nice clean sand, and then five pails of gravel 
that had no stones in it larger than would pass 
through a ring having a clear diameter of two 



32 MECHANICS 

inches. All this gravel, sand, and cement being 
in one heap on the board, Fred and Nick worked 
at it steadily for more than ten minutes, mixing 
it up until the sand and cement were thoroughly 
and evenly blended with the gravel. Fred then 
sprinkled the mixture with clean water from the 
hose, while Nick kept shovelling it over and over 
until the whole was damp, but not so much so that 
the cement and sand were washed from the gravel. 
The whole mass looked like a pile of dirty stones 
that had just been under a light shower. 

"This," said Fred to Nick, "is a very important 
process, for if we make the stuff too wet, it will 
starve the concrete by washing away the cement, 
and if we leave it too dry the work will be rotten 
and crumble away." 

Fred might also have added that the proper 
proportioning of the materials was as essential as 
the proper mixing, and in this case, where we are 
making it one of cement, two of sand, and five 
of gravel — all by measurement — we must adhere 
closely to the rule or the walk will be uneven in 
texture and colour. 

The concrete being properly mixed, Fred and 
Nick began to shovel it into the trench, spread it 
to about four inches in thickness, and tamped it 



I I 



A PATHWAY OF CEMENT 33 

down until the top mass looked sloppy and muddy. 
While in this condition, a new lot of cement mixture 
was made, consisting of one part of cement and 
two parts of sand and the fine of the gravel that 
had been sifted. All were mixed thoroughly while 
dry, and afterward wet to the consistency of thick 
mortar. This was spread over the concrete to 
about one inch in thickness and levelled down by 
the notched straight edge until the proper thickness 
and level were obtained. The surface was then 
ready to smooth, or ''float," as the workman calls 
it, which always /^ndRo^f 

gives to the top of 
the work a nice, 
even, level appear- Laymg 7?ow&/s 

ance, and makes it ^ 






solid and firm. The 

"floating" is done ^'^'^' floats and trowels 

with a tool made of wood, as shown in Fig. 7, and 
may be finished off with a plasterer's steel float, 
merely to give the surface a better finish. 

The floating operation is laborious, for it must 
be done at once, while the operator is on his knees. 
Fred and Nick, however, worked away at it until 
they made a good job of the portion that they were 
putting down. All of the walk they could finish 



34 MECHANICS 

at one time was about sixteen or eighteen feet, 
so that the whole job required a number of days 
to complete. 

The first instalment being done, so far as the 
floating was concerned, it was now in order to make 
joints in the walk across the face, firstly for the 
purpose of marking it oflF into flag sizes, four feet 
square; secondly to prevent expansion. If there 
were no joints made in the walk, it would ''lift" 
up, crack, break, and ultimately be destroyed. 
Fred, who knew that the walk would contract in 
cold and expand in warm weather, explained this 
peculiarity to George and Nick, and having a 
"jointer" along with the floats which the father 
had sent, he, with Nick's help, ran some joints, at 
four-foot intervals, across the walk, while Nick 
pushed his spade through the joints to the ground, 
actually cutting cement and concrete into sections 
of four feet each. This would allow for expansion 
or contraction, and even admit the raising of some 
of the sections above the others, without cracks 
or breaks occurring. 

The first instalment of the walk being made, it 
was left to George to wheel damp sand and scatter 
it over the face of the walk about an inch thick, 
to keep the sun and rain from injuring it. 



I I 



A PATHWAY OF CEMENT 35 

Then he received instructions to wet the surface 
every morning for a week. At the end of two or 
three days the cement was hard, or ''set" enough 
to bear walking on, and in a week it was cleaned off 
for use. One peculiarity about concrete or cement 
work is, that it improves and gets stronger with 
age. 

The walk was complete in due time, in sections 
of about sixteen feet long, and proved quite sat- 
isfactory. Mr. Gregg was pleased with it, and he 
explained to Fred, George, and Jessie that it might 
have been made more ornamental, as there were 
many tools for rounding off the edges, indenting 
the surface, to make it less slippery, or for laying 
the flags off in panels; but in this case all were 
pleased with the way the boys had finished it. 



II 

BUILDING OF A BOAT HOUSE 

THE cement walk being finished to the satis- 
faction of all concerned, and the admira- 
tion of the neighbours, Fred turned his 
thoughts to the building of a boat house and work- 
shop. It was decided to make it 16 feet wide 
and 22 feet long, as these dimensions would suit 
the timbers in the old barn, and be ample for stowing 
away the boat and allowing space for a work bench. 
Lines for a foundation were set out, and stakes 
driven in the ground at the corners, alongside the 
cement walk and pier. A trench about two feet 
deep was dug on the two sides and ends; and in 
this were laid large rocks and stones, in a single 
course all round. Nick, who was quite handy at 
this kind of work, built up a wall of smaller stones 
laid in cement mortar. This mortar was composed of 
one part of cement to five of sand, and made quite 
thin and easy to spread. When the wall was high 
enough, about level with the highest part of the 
ground, it was levelled off by using smaller stones 



BUILDING OF A BOAT HOUSE 37 

and plenty of cement mortar. The level was ob- 
tained by laying a straight plank flat on the top 
of the cement finishing, and then applying an or- 
dinary spirit-level. Any errors in the level of the 
wall showed at once, and were made right by adding 
more mortar, or by taking some off the top of the 
wall. 

Timbers from the old barn were next pressed 
into service, chestnut wood that had served as 
girths and beams. Two pieces were cut, 22 feet 





Corner efWallplate 
Fig. 8. Framing studding 

long, and two of 16 feet. The ends were then 
halved, as shown in Fig. 8 — the simplest method 
of framing a corner — and the timbers were spiked 
and so squared as to make right angles at the 
corners. 

Fred then took the old window and door frames, 
and measured off on the foundation timbers the 
outside distance where each one was to be placed. 
He put the double doors in the end of his boat 
house, next to the river front. The other door and 



38 MECHANICS 

windows were set in the best places to provide 
an entrance opening on the cement walk, light 
above the work bench, and views over the river 
and grounds. Fred decided to build his house 
ten feet high; so a quantity of studding, 2x4 
inches in section, was taken out from the walls 
of the barn, and cut exactly ten feet long. These 
were to form the side walls between the corners, 



y 


J_ 


( 

Vv 


f 

r 


JLJ 




m 

o 
o 


JLJ- 


V 




— "f 

. .it. 


n 


i 


. J 


1 V 


^ i 




a i 


! I 


n 


1 T ■ 


1.3 


1 r 


^m 




'^m 



Pig. 9. Side of boat house frame 

doors, and windows. Heavier studs were found 
in the barn, and Fred wisely used them next the 
windows and doors. 

These heavy studs were set up in the places 
marked on the timber sills, also at the four corners, 
and were toe-nailed at the bottom to hold them in 
place. They were then made vertical or plumb, 
by aid of a spirit-level, and the corners were 



BUILDING OF A BOAT HOUSE 39 

braced temporarily to hold them in that position. 
The picture (Fig. 9) shows how the side of the 
building next to the cement work looked when the 
studding was all in place. The dark ends shown 
are the joists on which the floor is laid. The 
lower joists were 
made from tim- 
bers taken from 
the barn floor, 2 x 
8 inches wide and 
long enough to 
reach across the 
building. The 
joists on top were 
2x6 inches, by 
16 feet long. 
These latter floor 
beams were set 
about 15 inches 




Fig. 10. End of boat house frame 



apart, ready to receive the flooring plank, which was 
nailed solid to them. You will notice that cross pieces 
of studding are nailed between the studs at the win- 
dow openings. These form the tops and bottoms of 
the window frames. The spaces above and below 
are also filled in with short pieces of studding, to 
nail the clapboards to, as shown. The ends of the 



40 MECHANICS 

building were finished as shown in Fig. 10, a small 
window being left in each to admit light and air, 
also lumber, poles, or other stuff that could be 
put into the loft through these openings. Inside 
the building a trapdoor was to be left, so that 
Fred or George could get up to take in or hand 
out the stuff. 

The end (Fig. 10) shows how Fred and Nick, 
with George's help, built that portion, the collar 
beam, O O, and the rafter being seen, while the 
details in Fig. 8 give larger sketches of the manner 
of doing the work. The stone-work, as built by Nick, 
for foundation walls, is shown in both Figs. 9 and 10. 

All the clapboards having been taken off the 
barn and old sheds, the better portions were selected 
for covering the outside of the new frame, and a 
lot of old boards were used for lining the inside of 
the walls and nailing on to the rafters. The next 
thing was to lay on the shingles. These had been 
provided some days before by Mr. Gregg, who had 
figured out the number required. He found the 
roof would measure 24 feet in length, including 
the projections over the ends of gables, and that 
the length of the rafters was 17 feet each, including 
the overhanging eaves or cornice. This made 
the whole stretch of length on both sides of the roof 



BUILDING OF A BOAT HOUSE 41 

34 feet. Multiplied by 24 feet, the length of the 
roof, this was 816 feet. To cover an area of 816 
feet about 8,000 shingles would be required, as 100 
surface feet require nearly 1,000 shingles, laid 4 
inches to the weather, according to the usual custom. 
Mr. Gregg explained to Fred what is meant by the 
term ''weathering," applied to shingles, clapboards, 
slates, or anything similar. The "weathering" part 
of a shingle is that portion of it exposed to the 
weather, when in place on the roof. It makes no 
difference how wide or how narrow a shingle may be, 
it is that portion showing from the lower end of one 
shingle to the lower end of the next one above it, 
that is the "weathering." This is generally four 
inches wide and it runs from end to end of the roof. 
Another thing Mr. Gregg explained — the term, 
''a square of shingling." ''In this case, as in floor- 
ing, clapboarding or similar work, a square is an 
area 10 x 10 feet; or 100 superficial feet. In 
nailing down shingles," went on Mr. Gregg, "the 
nails should be driven so that the next course or 
layer will cover up the nail heads, thus protecting 
them from rain and damp, and preventing them 
from rusting. When laying the shingles, after 
the first courses are on, which should be laid double 
at the eaves, a string or chalk line must be stretched 



42 MECHANICS 

from one end of the roof to the other, four inches 
up from the ends of the first courses. This string 
or chalk line may first be rubbed over with chalk 
or soft charcoal, and when drawn tight from each 
end, it may be 'struck' or 'snapped' by raising 
it up in the middle and letting it strike the roof 
suddenly so that a mark will be left on the shingles 
from end to end. This will be the guide for the 
thick ends of the shingles to be laid against when 
nailing on the next course, and the process must 
be continued until the ridge, or top of the roof, 
is reached. When you paint your boat house, 
don't forget the roof, for a good coat of paint on 
the shingles will lengthen the life of the roof fully 
five years." 

Fred, to whom these instructions were more 
particularly given, told his father he understood 
the whole matter, and he was directed to go on 
with the work. In the meantime the father or- 
dered the shingle-nails required; five pounds for 
each thousand shingles, or forty pounds altogether. 

The building being small, the whole work was 
soon completed, windows put in, doors hung, and 
floors laid; and Mr. Gregg was greatly pleased 
with the manner in which Fred had managed the job. 

The next thing was to take down the heavy 




Photograph by Frank H. Taylor 

Boat House and V\'ork-shop 



'A Good Coat of Paint on the Shingles Will Lengthen the Life of the Roof 
Fully Five Years." 



BUILDING OF A BOAT HOUSE 43 

timbers of the barn, still standing. Fred saw at 
once that they were too heavy to be removed 
without mechanical aid or more human help, so 
he brought from his father's stable a rope and set 
of pulley-blocks like the ones shown in Fig. 11. 
Nick, who had seen some service at sea, hooked 
the block into a loop formed by a short piece of 
rope tied over a limb projecting from one of the 
trees. The question of lifting the timber now 
was an easy one, as another short rope was tied to 
the heavy post W, in this case the weight P being 
the power. Each of the blocks shown contains 
pulleys which make the relation of the weight to 
the power as one to four. The weight being sus- 
tained by six cords, each bears a sixth and a weight 
of six pounds will be kept in equilibrium by a power 
of one pound. The blocks used in a system of this 
character are called single if there is one pulley 
in each, double if there are two, treble if there 
are three, and quadruple if there are four. 

Fred, George, Nick, and Jessie who liked to 
help whenever she could, counted for four times 
their number when they all pulled together on the 
rope P. It was astonishing to the youngsters how 
easily the heavy timbers were taken down and 
piled in a nice heap. 



44 MECHANICS 

Two timbers, each about twenty-five feet long, 
were chosen and marked, to be used for shdes 
or ways, on which the proposed boat could be 
hauled in and out of the boat house. It was quite 
a distance from the timber to the river end of the 
boat house, and, the former being heavy, Fred 
decided to make an inclined plane of planks — 
of which there was an abundance — so that the tim- 
bers could be slid or rolled down to the river. It 
took but a few minutes to lay the planks, and as 
the incline was gentle, rollers were used and the 
timbers went down as easily as the big rock had 
done. This pleased the younger children very 
much. 

"When papa comes home," said Jessie, "I'm 
going to get him to tell me about the 'inclined 
plane' as well as the ropes and pulleys." 

The two timbers were rolled into the river and 
floated to the boat house, where one end of each was 
raised to the floor level at the doorway and made 
fast; the other end sank to the bottom, where Nick 
dug down and made a bed for it to rest in. These 
beds were made deep enough to bury the ends, 
and large stones were then thrown in to keep them 
from moving, but these were not allowed to reach 
within 18 inches of the surface of the water, which 



BUILDING OF A BOAT HOUSE 45 

was then at its lowest mark. The timbers were kept 
about three feet apart, ample space to admit of any 
ordinary launch or row boat being taken into the 
boat house. 

"Oh, Fred," said Jessie, ''do you think those 
two sticks will be strong enough to hold the boat 
while you are pulling it up.^^" "Why, yes; strong 
enough to hold a dozen boats no larger than the 
one we intend having made. I don't know how 
much weight these timbers will support, nor how 
heavy our boat will be with the engine in it, but 
I'm sure the timbers are strong enough." 

Jessie's question, however, caused Fred to think 
over the matter, and he set to work to find out 
how to tell the strength of timber beams. He 
discovered that to be able to determine the strength 
of beams and wooden pillars under all sorts of 
conditions required considerable training in me- 
chanics and mathematics, but that the case before 
him was comparatively easy. A general rule for 
finding the safe carrying capacity of wooden beams 
of any dimensions, for uniformly distributed loads, 
is to multiply the area of section in square inches, 
by the depth in inches, and divide their product 
by the length of the beam in feet. If the beam 
is of hemlock, this result is to be multiplied by 



46 MECHANICS 

seventy, ninety for spruce and white pine, one 
hundred and twenty for oak, and one hundred and 
forty for yellow pine. The product will be the 
number of pounds each beam will support. For 
short-span beams, the load may be increased 
considerably. Fred, who had some knowledge on 
the subject, acquired at the training school, deter- 
mined to pursue his studies in this direction. 

In talking over the matter of nails with his father, 
their holding power was mentioned, and Mr. Gregg 
told Fred of a test that had been made some time 
ago by the U. S. Ordnance Department, where cut 
and wire nails had been tested respectively, showing 
a decided superiority for the former, both in spruce, 
pine, and hemlock. Thus in spruce stock nine series 
of tests were made, comprising nine sizes of common 
nails, longest 6 inches, shortest 1^ inches; the cut 
nails showed an average superiority of 47.51 per cent. ; 
in the same wood six series of tests, comprising 
six sizes of light common nails, the longest 6 inches 
and the shortest 13^ inches, showed an average su- 
periority for cut nails of 47.40 per cent.; in 15 series 
of tests, comprising 15 sizes of finishing nails, 
longest 4 inches and shortest 1% inches, a superiority 
of 72.22 per cent, average was exhibited by the 
cut nails; in another six series of tests, comprising 



BUILDING OF A BOAT HOUSE 47 

six sizes of box nails, longest 4 inches and shortest 
1 J^incheSjthe cut nails showed an average superiority 
of 50.88 per cent.; in four series of tests, compris- 
ing four sizes of floor nails, longest 4 inches and 
shortest 2, an average superiority of 80.03 per cent, 
was shown by the cut nails. In the 40 series of 
tests, comprising 40 sizes of nails, longest 6 inches 
and shortest 13^8 inches the cut nails showed an 
average superiority of 60.50. 

Speaking of the ropes used in blocks, while taking 
down the old barn timbers, Mr. Gregg suggested 
that it would not be a bad idea if the boys were 
taught a few general items concerning hempen 
ropes; so he asked them to memorize the following: 
A rope 3^ inch in diameter will carry 450 pounds, 
and 50 feet of it will weigh one pound. If ^ inch 
in diameter, it will carry 3,000 pounds and 7 feet 
will weigh one pound. When a rope is % inch in 
diameter, it will carry 3,900 pounds, and 6 feet will 
weigh 1 pound. A rope one inch in diameter, the same 
as we have in our blocks, will carry 7,000 pounds, and 
3 feet 6 inches will weigh one pound. "It is not 
likely that sizes greater than these will ever be used 
by you. If they are, you can obtain a fair knowledge 
of their strength by finding their areas, and com- 
paring them with the areas of the ropes given, 



48 MECHANICS 

taking the rope having one inch in diameter, as 
a constant example." 

Wire ropes are much stronger than hempen 
ones, whether made of steel, brass, or bronze. The 
care and preservation of ropes is deserving of 
consideration, particularly in localities where the 
atmosphere is destructive to hemp fibre. Such 
ropes should be dipped when dry into a bath con- 
taining 20 grains of sulphate of copper per gallon 
of water, and kept soaking in this solution some 
four days, before they are dried. The ropes will 
thus have absorbed a certain quantity of sulphate of 
copper, which will preserve them for some time, 
both from the attacks of animal parasites and 
from rot. The copper salt may be fixed in the 
fibres by a coating of tar or by soapy water. In 
order to do this the rope is passed through a hot 
bath of boiled tar, drawn through a ring to press 
back the excess of tar, and suspended afterwards 
on a staging to dry and harden. 

The figures given are intended for new manila 
ropes, and do not hold good for ropes made of 
inferior hemp. It is always safer never to load 
a rope to more than 60 per cent, of its capa-city, 
and not even this much when it is old and weathered. 

Jessie reminded her father of his promise to 



BUILDING OF A BOAT HOUSE 49 

give them some information regarding the power of 
blocks and tackle and the qualities of the inclined 
plane. Accordingly, Fred, George, and Jessie joined 
their father in his den after supper, and George 
placed his blackboard in a convenient place with 
chalk, rule, and other requisites. 

When all were seated, the father said: "Some 
time ago I tried to explain to you the uses of the 
lever in quite a number of diflFerent 
situations; to-night I'm going to 
show you how the various ropes and 
pulley blocks are made to do service 
for mankind. These devices are 
used very generally, especially in 
building operations, where heavy 
beams, girders, or blocks of stone 
have to be raised. On board ship, 
it is the favourite mechanical power 
by which rigging is raised, cords and 
ropes tightened, and goods lifted 
from or lowered into the hold. 

"The pulley, the main feature of 
the third mechanical power, may be 
explained almost on the same principle as the lever, 
as you will see upon examining the sketch (Fig. 11) 
I now make on the blackboard. 




Fig. 11. Blocks and 
tackle 



50 



MECHANICS 






"The pulleys seen in the blocks around which 
the rope runs may be considered so many levers 
whose arms are equal, and whose centres are 
fulcrums. 

"In describing this power, it will perhaps be 
better to begin with the first and simplest form of 
the combination. The pulley, weight, and rope 
I show now (Fig. 12) is the simplest form of mak- 
ing use of this power. It is called a snatch-block 
and often employed for drawing water 
from wells, or for hoisting light weights. 
It is very handy, but we do not get 
any additional power from it, though 
we get a change of direction and quick 
movement. From its portable form, 
its low cost, and the handiness with 
which it can be applied, this arrange- 
ment is one of the most useful of our 
mechanical contrivances. 
"When pulleys are adjusted, as I show you in 
this sketch (Fig. 13), the block which carries the 
weight is called a movable pulley, and the whole, as 
shown, a system of pulleys. 

"In this illustration, suppose the weight is 20 
pounds. It is supported by two cords, A and B; 
that is, the two sections of the cord support 10 



S 



Fig. 12. Theory of 
block and tackle 



r r~i 




BUILDING OF A BOAT HOUSE 51 

pounds each. Now, the cord being continuous, 
the power must be 10 pounds. 

*'We leave out of con- 
sideration the weight of *■ 
pulley and the friction of 
the various parts. 

"We have seen that the 
weight is sustained by two 
cords; if, therefore, it has 
been raised two feet, each 
cord must be shortened 
two feet. To do this, the 

power P must run down Fig. is. Double block and tackle 

four feet. To get the full value of this machine 
the cords must be parallel. 

"If we increase the number of movable pulleys, 
as sketched at Fig. 14, to three, the relation of 
P to W will be as 1 to 8 and the distance through 
which P will travel will be eight times that through 
which W is raised. 

"If we apply this principle to the sketch (Fig. 11), 
which illustrates the blocks you used to-day in 
lifting the large timbers, and which is the usual 
form of pulley employed to lift heavy weights, 
you will notice that there is a four-sheave block 
at the top, and a three-sheave block at the bottom. 



52 MECHANICS 

with the end of the rope fixed from the top block. 
The three-sheave block is movable. A power of 
10 pounds will, with this form of pulley, balance 
a weight of 60 pounds. 

"Suppose a block of stone weighing 8,000 lbs. 
is to be raised to the top of a wall and we use a 
system of pulleys where each of the two blocks has 
four pulleys; we shall find that it will require a 
power of 1,000 pounds to raise it. 

*'Now, as to the inclined plane: this is called 
the fourth mechanical power, and it is not in any 

way related to the lever, but 
is a distinct principle. Some 
writers on the subject reduce 
the number of mechanical 
powers to two, namely, the 
lever and the inclined plane. 
The advantages gained by 
this are many for just so much 
as the length of the plane ex- 
ceeds its perpendicular height 
is an advantage gained. Sup- 
pose ABC (Fig. 15), I make 

Fig. 14. Multiple block. ^^ ^hc sketch, is a plane stand- 
and tackle j^^g ^^ ^^^ |.^ble. If length 

A B is three times greater than the perpendicular 





BUILDING OF A BOAT HOUSE 53 

height C B then a cylinder at R P may be sup- 
ported upon the plane A B by a power equal to a 
third of its own weight. 
That is, a block of that 
weight would prevent 
the roller or cylinder 
from going farther. 
From this we gather that 
one third of the force 
required to lift any giv- 
en weight in a perpen- 
dicular direction will be quite sufficient to raise 
it the same height on the plane; allowance, of 
course, must be made for overcoming the fric- 
tion, but then, you see, you will have three times 
the space to pass over, so that what you gain in 
power, you will lose in time. We see the use of 
the inclined plane every day we pass a building 
under construction, where the workmen wheel 
bricks, mortar, and other materials from the street 
to the floors above, using long planks for the plane 
or tramway. Merchants, too, often make use of 
an inclined plane when rolling heavy boxes and 
packages from the street to the floors of their ware- 
houses. 

"An excellent, practical illustration was given 



54 MECHANICS 

you to-day when Nick and Fred built the ways 
on which the proposed boat is to be slid into the 
new house. It would require five or six strong 
persons to lift the boat bodily into the new house; 
but I expect two or three will easily slide it up 
into the building on the ways; and by arranging 
a winch — another mechanical contrivance — at one 
end of the boat house, Fred, or George, for that 
matter, will be able to haul the boat up. The 
winch for this purpose will be a very simple affair, 
merely a ready adaptation of the wheel and axle, 
as I will show you later. Now, however, we are 
talking about inclined planes, and to illustrate 
its early application to the building arts, it is only 
necessary to tell a few things we know regarding 
the moving and raising of the great stones used in 
building the Pyramids. For centuries it was a 
mystery how the heavy stones in these structures 
had been placed in their present positions. Re- 
cent investigations have led many scientific men 
to believe the stones were taken up inclined planes, 
on rollers, and then put in place by the workmen, 
who moved them to the diflferent sides of the build- 
ing on strong timber platforms, where rollers, or 
rolling trucks, carried the load. According to one 
authority, there are the remains of the approach 



BUILDING OF A BOAT HOUSE 55 

to an inclined plane near the Great Pyramid, 
which, if continued at the angle, as now seen, would 
rise to the apex. According to this writer, the 
foot of the plane was more than a mile from the 
building, fifty or sixty feet wide, and had been one 
huge embankment, formed of earth, sand, and the 
clippings and waste of stone made by the workmen. 
This, of course, would be an expensive and a tedious 
method, but in those days time and labour went 
for little. Every time a course of stones was laid 
and completed, the plane was raised another step, 
to the height of the next tier of stones. The same 
angle of incline was probably maintained during 
the whole period of erection, and this angle, you 
may rest assured, was made as low and easy as 
possible; for the Egyptian engineers were not slow 
in adapting the easiest and quickest methods 
available. 

"This method of conveying the heavy stones to 
their places in the Pyramids was simple and effec- 
tive, with no engineering difiBculties that could not 
be readily overcome. Moreover, it was really 
the very best method considering the narrow limits 
of their appliances. 

"You may ask, 'How were these big stones 
carried to the foot of the inclined plane?' The 



56 MECHANICS 

quarries, in some cases, were five hundred miles dis- 
tant, and most of the stones had to be brought 
across the Nile to the works. We know from the 
monuments, and from the papyrii that have come 
down to us from remote periods, that many of the 
stones were brought down the river on large rafts 
or floats, and on barge-like vessels; and we also 
know that many of the larger ones were hauled or 
dragged down from the quarries at Assowan to 
Memphis, alongside the river, a distance of 580 
miles. This is particularly true of the obelisks, 
for all along an old travelled road evidences have 
lately been found that these stones had been taken 
that way, and that resting places for the labourers 
had been provided at stations about twelve miles 
apart, along the whole distance. It has been esti- 
mated that a gang of men — say forty — well 
provided with rollers, timbers, ropes, and necessary 
tools, could easily roll an obelisk like that in Cen- 
tral Park, New York, twelve miles in twelve hours; 
and doubtless this was the system employed in 
conveying those immense stones that great distance. 
''A large number of obelisks were erected near 
Memphis, though there are none there now, for 
the Greek and Roman engineers, at the command 
of the rulers, took a number down and carried 



BUILDING OF A BOAT HOUSE 57 

them to the city of Alexandria; but we have less 
knowledge of how these later engineers transferred 
the stones to the newer city, than we have of the 
methods of the older. The beautiful column known 
as Pompey's Pillar was once an obelisk, and was 
transformed into a pillar, by either Greek or Roman 
artisans, it is not clear which. The work of putting 
those huge stones in place was not easy, as Com- 
mander Gorringe discovered when he stood the 
New York obelisk in the place it now occupies. 

''But let us get back to our inclined plane. 

''I have shown you how a weight or roller acts 
on the incline, but I did not explain it clearly, 
nor in a scientific way, as I do not want to puzzle 
or confuse you with terms and problems you can- 
not understand. I will, however, give you another 
illustration or two on the subject, in which another 
factor plays a part, namely — gravitation. Let 
us suppose you have two golf balls laid on a table 
that is perfectly horizontal or level in every direc- 
tion; they will remain at rest wherever placed, 
but if we elevate the table so that the raised end 
is half the length of the top higher than the lower 
end, the balls will require a force half their weight 
to sustain them in any position on the table. But 
suppose they are on a plane perpendicular to the 



58 MECHANICS 

table top, the balls would descend with their whole 
weight, for the plane would not contribute in any 
respect to support them; consequently they would 
require a power equal to their whole weight to hold 
them back. It is by the velocity with which a 
body falls that we can estimate the force acted upon 
it, for the effect is estimated by the cause. Suppose 
an inclined plane is thirty-two feet long, and its 
perpendicular height sixteen feet, what time should 
a ball take to roll down the plane, and also to fall 
from the top to the ground by the force of gravity 
alone? We know that by the force of attraction 
or gravitation, a body will be one second in falling 
sixteen feet perpendicularly, and as our plane in 
length is double its height at the upper end, it will 
require two seconds for the ball to roll down from 
top to bottom. Suppose a plane sixty-four feet 
in perpendicular height, and three times sixty- 
four feet, or one hundred and ninety-two feet long; 
the time it will require a ball to fall to the earth 
by the attraction of gravitation will be two seconds. 
The first it falls sixteen feet, and the next forty- 
eight feet will be travelled in the same time, for 
the velocity of falling bodies increases as they 
descend. It has been found by accurate experi- 
ments that a body descending from a considerable 



BUILDING OF A BOAT HOUSE 59 

height by the force of gravitation, falls sixteen 
feet in the first second, three times sixteen feet in 
the next; five times sixteen feet in the third; seven 
times sixteen feet in the fourth second of time; 
and so on, continually increasing according to the 
odd numbers, 1, 3, 5, 7, 9, 11, etc. Usually, the 
increase of velocity is somewhat greater than this, 
as it varies a trifle in different latitudes. In the 
example before us we find that the plane is three 
times as long as it is high on a perpendicular line; 
so that it will take the ball to roll down that dis- 
tance (19£ ft.) three times as many seconds as 
it took to descend freely by the force of gravity, that 
is to say, six seconds. 

"The principle of the inclined plane is made 
use of in the manufacture of tools 
of many kinds, as in the bevelled 
sides of hatchets, axes, chisels and 
other similar tools, the examples 
of which are in a great measure 
related to this power, though many 
of them partake largely of the 
wedge, of which we shall now ^^s- i^. Action of 

the wedge 

have something to say. 

"The wedge may be a block of wood, iron, or 
other material, tapered to a thin edge, forming a 




60 MECHANICS 

sort of double inclined plane, A P B, (Fig. 16) 
where their bases are joined, making A B the 
whole thickness of the wedge at the top. In split- 
ting wood as is shown in the illustration, R R being 
the wood, the wedge must be driven in with a large 
hammer or heavy mallet which impels it down 
and forces the fibres of the wood to separate and 
open up. The wedge is of great importance in 
a vast variety of cases where the other mechanical 
powers are of no avail, and this arises from the 
momentum of the blow given it; which is greater 
beyond comparison than the application of any 
dead weight or pressure employed by the other 
mechanical powers. Hence, it is used in splitting 
wood, rocks, and many other things. Even the 
largest ships may be raised somewhat by driving 
wedges below them. Often, in launching a vessel, 
wedges are used to start it on its way. And they 
are also used for raising beams or floors of houses 
where they have given way by reason of having 
too much weight laid upon them. In quarrying 
large stones, it is customary to wedge or break 
oflf the rock by first drilling a number of holes, on 
the line of cleavage. Wooden wedges are then 
driven tightly into these and left there until they 
get wet, when they expand and split off the rock 



BUILDING OF A BOAT HOUSE 61 

as required. This method of quarrying large stones 
was well known to the old Egyptians, and employed 
by them in quarrying their famous obelisks. 

"Owing to the fact that the power applied to 
force a wedge is not continuous, but a series of 
impulses, the theory of the wedge is less exact 
than that of the other mechanical powers. Con- 
sidering the power and the resistance on each side, 
however, as three forces in equilibrium, it may 
be demonstrated that the 

Resistance (R) equals PX length of equal side 
.Back of wedge 

Then the mechanical advantage will be — 

R . I^ength of equal side 

P Back of wedge 

So that by diminishing the size of the back and in- 
creasing the length of the side — that is, diminishing 
the angle of penetration — the mechanical power of 
the wedge is increased. While I did not intend to 
inflict you with arithmetical or algebraical formulae, 
I have been compelled to give you that simple ex- 
ample which I know you can all work out, as it is 
concise, and the same would be long and tedious if 
rendered in text." ^ 

Next morning, as Fred and his father were out 



62 MECHANICS 

on the new place early, looking over the boat 
house, the slide for the boat, and some other mat- 
ters, Mr. Gregg suggested that a winch be placed 
at the upper end of the house, to haul the boat out 
of the water. He also suggested that Fred prepare 
for work on the boat at once, and provide himself 
with all the tools and materials necessary. He 
promised to call on a friend of his in the city, who 
is a noted boat builder, and ask him the best method 
to adopt in building the craft. 

"Perhaps," said the father, "it might be a good 
plan to buy a full set of shapes or patterns from 
some one of the professional boat builders who adver- 
tise such. They are sold at a very low rate — being 
made of paper — and many firms sell all the 
material that is required to build a boat complete; 
with the sweeps, ribs, and curved stuff cut out 
to the required shape and numbered all ready to 
set up. 

"What we want, Fred," continued the father, 
"is a boat sixteen or eighteen feet long, just the 
size of the one belonging to your friend, Walter 
Scott; that is plenty large enough for all our 
purposes. His boat can stand as a kind of a model 
for you to work after in case you do not thoroughly 
understand the patterns you are to get, or the 



BUILDING OF A BOAT HOUSE 63 

manner of arrangement. The gasolene motor we'll 
order from some manufacturer, with whom we'll 
arrange to install it, with a suitable propeller and 
necessary attachments." 

Fred was quite satisfied with all his father had 
said and started to get ready. Jessie began to 
question him about several things she did not fully 
understand in her father's talk the night previous. 
Fred explained matters, made them quite clear to 
her, and then asked her to get her memorandum 
book and write down the following, which 
he said, she would often find useful: "There are 
six mechanical powers, two of which father has 
not told us about, but will no doubt do so, before 
long. These are called, the Lever, Pulley, Wheel 
and Axle, Inclined Plane, Wedge, and Screw. 
The Screw and the Wheel and Axle, you have 
yet to hear about. Now, study carefully the fol- 
lowing rules : 

''The Lever, — Rule: The power required is to the 
weight as the distance of the weight from the ful- 
crum is to the distance of the power from the 
fulcrum. 

** The Pulley, — A fixed pulley gives no increase 
of power. With a single movable pulley the power 
required will equal half the weight, and will move 



64 MECHANICS 

through twice the distance. Increasing the number 
of pulleys, diminishes the power required. Rule: 
The power is equal to the weight, divided by 
the number of folds of rope passing between the 
pulleys. 

^'The Wheel and Axle, — Rule: The power is to 
the weight as the radius of the axle is to the length 
of the crank or radius of the wheel. 

^'The Inclined Plane, — Rule: The power is to 
the weight as the height of the plane is to the 
length. 

'Wedge, — Rule: Half the thickness of the head 
of the wedge is to the length of one of its sides as 
the power which acts against its head is to the effect 
produced on its side. 

'^'The Screw, — Rule: As the distance between 
the threads is to the circumference of the circle de- 
scribed by the power, so is the power required to 
the weight." 

Fred told George also to copy the foregoing in 
his memorandum book, so that he would be able 
to work out any problems for himself. 



Ill 

BRroGE AND BOAT WORK 

THE next day Fred and his father talked over 
the proposed boat, the result being that 
Walter Scott was asked over the telephone 
if he would come down in his launch to the Gregg 
property in the evening, as Mr. Gregg and Fred 
would like to see the craft, hear all about it, and find 
out if it had any defects that might be avoided 
in the building of another one. Walter said he'd 
be glad to sail down, and would take his sister to 
see Jessie. In the meantime some addresses of 
boat builders were handed to Fred, with instructions 
to write and ask for catalogues, prices of materials, 
and the other information usually sent out to pro- 
spective customers. Fred immediately wrote to 
a number of firms, including several who manu- 
factured motors and other requisites for small 
launches. 

A little after the city clock struck four, Jessie, 
who was home from school, saw The Mocking- 
Bird sailing down the river at good speed, with 

65 



66 MECHANICS 

Walter, his sister Grace, and their mother on board. 
Fred went down to the water's edge, and helped 
Walter haul the boat to the unfinished landing place, 
where Mrs. Scott and Grace were safely landed. 

Fred and Walter soon became deep in "boat talk," 
and kept it up until the arrival of Mr. Gregg, who 
began to make inquiries regarding the speed, ca- 
pacity, and safety of The Mocking -Bird. All his 
questions were intelligently and favourably answered 
by Waiter, a bright and earnest little fellow. He was 
some months the senior of Fred, but was not so 
strong or robust looking. 

"She's just 18 feet long over all," said he, "with 
a 5-foot beam, a draft aft of about 18 inches, and a 
forward draft of 1 foot. She is fitted with a 6-horse- 
power gasolene engine, and her speed is from 8 to 9 il 
miles an hour." 

An illustration of her, as she appeared when partly 
built, is shown in Fig. 17, where a plan and a sec- 
tion of her length may be seen. The manner of 
her construction is also shown, also the lines of ribs, 
portion of inside lining, position of motor, rudder, f | 
and propeller. 

Mr. Gregg also ascertained from Walter that his 
father had sent to a firm who made a business of 
preparing the complete woodwork for many kinds 



*i 



BRIDGE AND BOAT WORK 



67 




s 



bo 



68 MECHANICS 

of boats on the "knockdown" system, selling the 
whole material ready to set up without the aid of 
an expert. Printed instructions came along with 
each boat, so that the buyer would have but little 
diflSculty in setting up the wood-work and making 
it ready for use. An expert workman had been 
engaged by Walter's father to install the engine, 
line up the propeller shaft, and connect the wheel and 
shaft to the engine. On the arrival of the materials 
— within a week after the order was sent — Walter 
had gone to work; and inside of fourteen days. The 
Mocking-Bird took to the water. 

So fully and so satisfactorily did Walter explain 
to Mr. Gregg all that he asked about, that Fred 
was able at once to order the material for a similar 
launch, to be sent on immediately. In order to hurry 
matters, a cheque was inclosed with the order, and 
Fred, Walter, and George walked over to the post- 
oflBce with the letter, so that it went by the night 
mail. 

On returning, it was suggested that the boys, 
Grace, and Jessie go for a sail on the river, and all 
were soon at the landing. Walter adjusted his 
engine and made all ready as George and the girls 
got on board, while Fred cast off the rope which 
held the boat to the dock, then stepped after them. 



BRIDGE AND BOAT WORK 69 

The engine was started, Fred took the tiller, and 
they were soon afloat, sailing with the tide in their 
favour at a rapid speed, and returning to the landing 
place inside of an hour, well pleased with their 
little outing. Fred showed Walter his new boat- 
house and workshop, explained to him how Nick 
and he, with the help of George and the advice 
of his father, had completed the work and the 
building. He also pointed out other work he was 
going to do as soon as his boat was finished. 

Though not yet dark, it was getting rather late, 
and Walter's mother advised that they start for 
home as soon as he was ready. So wishing Fred 
every success in the building of his boat, Mrs. Scott, 
her daughter, and Walter left for home. 

** Well, Fred," said Mr. Gregg, when his family were 
all seated in the living room, ''y^^ ^^^ iiow in for 
quite a job, one that will test your working qualities; 
but I am sure you will come out with flying colours. 
You will meet difficulties, but you must overcome 
them, and when the boat is finished, painted, and 
ready to name, you can have some of your friends 
up for the launching. Mother will have a special tea 
for you all, and we'll christen the new craft. Mean- 
time we must think over the matter of a name, 
and decide upon one we shall all like." 



70 MECHANICS 

Next morning, Fred and his father went down 
to the river's edge to examine the httle ravine that 
had been cut out by the spring and fall freshets. 
It was a small affair, only about six feet deep and 
ten or twelve feet wide. At present, the opposite 
side was reached by crossing a couple of planks, 
safe enough while the land had been in a measure 
unoccupied. To leave it so now would be a dif- 
ferent matter, as Jessie or her mother, attempting 
to cross, might easily fall over; so it was decided to 
have a foot-bridge built over the creek, which was 
nearly dry the greater part of the year. There was 
plenty of material on the ground for the purpose, 
and Fred was asked by his father to get Nick to 
help, so that the bridge might be ready as soon as 
possible. 

Fred felt he was getting to be quite an important 
person when his father trusted him with work 
which must necessarily entail considerable expense, 
but he accepted the responsibility with pleasure, 
and promised to commence at once, so as to have 
it finished by the time the material for the boat 
arrived. So, when Nick arrived, operations began 
immediately. 

Taking a tape line, Fred sent the Italian to the 
other end of it, and they picked out a favourable 



^m 






.^j^p's^f^li^ 


^i>^.--.t/ 




"'^^'v^^^ 


PW^SBF^ 


w^ l^Br^<* 


JRjaw^H ^ 


^^ w 


mI^L ^- ^ 


#AJi^jL^» -."^^^#1^ { j^.fe ^'t. '- .» g<L. 


^. 1 


—M ^ ] 


^^^ 



The Creek 



I 



BRIDGE AND BOAT WORK 71 

location to measure across, making it over 11 feet 
at the narrowest spot from one edge to the other. 
Allowance was then made for bearings five feet on 
either side of the span, so that timbers 21 feet long 
would be required to cross the chasm. This width 
would require three string-pieces, or chords, to run 
across, one on each side, and one in the centre. 
These, covered with three-inch plank from end 
to end, would make a good, solid deck sufficient 
for all purposes. The planks were cut off seven feet 
long, to have the deck of the bridge, over all, exactly 
seven feet wide. 

Among the timbers taken from the old barn 
were nine pieces, measuring 22 feet in length, 8 x 10 
inches in section, so Fred decided to make use of 
three of these just as they were, without cutting, 
and to place them on their edges to get the most 
strength out of them. He then had six posts cut 
off the old cedar fence posts, about two feet long, 
which were sunk into the ground their whole length, 
as shown in Fig. 18, three on each side of the creek, 
and the tops made level, so that a flat timber or 
plank would rest on them, touching each one. This 
plank was made nine feet long, so as to project 
over the posts about a foot at each end. This 
was, of course, the same at each end of the bridge. 



72 MECHANICS 

After the flat timbers had been laid on the ends of 
the posts and fastened with spikes, there were 
laid the three long timbers spanning the gully. The 
spaces between were equally divided/ and then 
covered with three-inch planks taken from the floor 
of the old barn. The boards were cut off to the 




Fig, 18. Frame of foot-bridge 

proper length and fastened down on the three 
timbers with spikes five inches long, the planks not 
laid close together, but kept about three-eighths of 
an inch apart, in order to let the water run off after 
a rain, as well as to allow air to circulate underneath 
and between the joints to prevent the planks from 
decay. 

In order to make the bridge safe, it was necessary 
to build a rail on each side. Two pieces of timber 
about 20 feet long and 6x6 inches square were 
used for the rails, while posts and braces were made 



BRIDGE AND BOAT WORK 73 

of timber of about the same dimensions. The bot- 
toms of the posts were halved, so that they could be 
spiked or nailed to the long outside string-pieces, 
as shown in the illustration. Tenons were made 
on the top of these posts, and these fitted 
into mortises made in the top rails, and all 
were then put together and fastened with wooden 
pins. [i 

Nick dug away the surplus earth from the ap- 
proaches to the bridge, and made an easy grade to 
its deck. This completed the work all but the 
painting, which was left to be done some other 
day. 

Mr. Gregg inspected the bridge, pronounced it all 
right, and congratulated Fred on his workmanship, 
at the same time saying a good word to Nick and 
George, both of whom had helped very much to 
make the effort a success. 

In the evening Mr. Gregg told Fred and George 
that a friend of his had given him a copy of 
the rules to be observed when running a 
launch, so he asked the boys to get their note- 
books, and take these down as he read 
them out. Even Jessie, too, he thought, ought 
to be acquainted with the rules, as she might be 
called upon some time to make use of them, so 



74 MECHANICS 

three pencils were soon at work, as the father 
read out the following: 

"1. When at the wheel, remember as a first consideration, 
that you cannot entertain the boat's occupants as well as 
steer. 

"2. Keep your course, and know what that course is. 

"3. Regulate your speed to the company you are in. 
Marine motors are, as a rule, very flexible. 

"4. Do not cut corners. 

**5. When approaching a landing, learn to judge exactly 
the distance j^our boat will travel after your propeller has 
stopped, so as to run alongside without using your reverse 
gear. This requires some practice, but is amply rewarded by 
time saved, in the long run, and decrease of wear and tear on 
engine, gear, and propeller. Any one can get to a landing in 
time by alternately running full speed ahead and then 
astern. 

*'6. When aboard your boat, and facing the bow your 
right hand is starboard, your left, port. Keep to the 
right. Should you be overtaking any one, it is your duty 
to pass clear on their left. The above applies only to narrow 
waters. 

"7. When going up or down stream, should you wish to 
cross over to the other side and return, and another boat is 
overtaking you on your left, don't attempt to cross its bow; 
slow down until it has passed. 

"8. Keep clear of non-engined crafts. You have greater 
freedom of action than they; it costs you nothing, and their 
occupants appreciate your courtesy. 

"9. Do not tow canoes or skiffs alongside. If towed 
at all, they should be right aft with as short a towline as 
possible. 



BRIDGE AND BOAT WORK 75 

"10. Finally; remember the rules of the road — 

" * Green to green or red to red 
Perfect safety — go ahead 
If to starboard red appear 
'Tis your duty to keep clear. 
When upon your port is seen 
A steamer's starboard light of green, 
There's not so much for you to do 
As green to port keeps clear of you.' " 

The children all promised to memorize these rules. 

As the stuff for the boat was not expected for 
some days, Fred and Nick kept at work about the 
new boat house, and building up the landing dock. 
The former fitted up a work bench, and put his little 
shop in readiness for actual use. Fred also hunted 
for a nice stick of timber among the old barn ruins, 
on which to set up the boat. A good piece found, 
he cut it to a length of 20 feet, and then he and 
Nick got it into the boat house, where Fred planed 
it off a little with a rough jack plane, keeping a 
sharp lookout for nails, sand, or gravel. Nothing 
destroys the cutting edges of tools more than nails, 
bits of iron, glass, sand, or small pebbles, which 
sometimes escape the vigilance of the workman. 
Especially is this true of saws, which Fred knew quite 
well since he had once run a good sharp saw against 
a nail, while cutting a piece of timber in two. This 



76 MECHANICS 

taught him a lesson he never forgot, and whenever 
he had to cut up old material, he was always careful 
to examine it all round, and to scrape or brush off 
all the dirt and sand from the parts through which 
the saw teeth had to travel. In planing, or "dress- 
ing" the stick of timber, the same precautions were 
taken, and the surface of the wood was made as 
clean and free from dirt and sand as it possibly 
could be. Notwithstanding all this, Fred found 
it almost impossible to keep the cutting iron of his 
jack plane sharp enough to take off shavings. He 
had to sharpen it every few minutes. This is nearly 
always the case when working up wood which has 
previously been used. However, he managed to 
*' dress" his stick very nicely, and after finishing 
it, laid it down along the middle of the floor of the 
shop, putting blocks of wood under it here and there 
to raise it up from the floor five or six inches. It 
was then made level on top and fastened down so 
that it would not move or get out of line. This was 
about all they could do on the boat until the 
materials arrived. Nick had managed to fill in 
the space between the two walls of the little pier 
with heavy bowlders, and had strengthened the 
whole with coarse rubble-stone work in such a manner 
that there was little danger of injury from floating 



BRIDGE AND BOAT WORK 77 

ice or flood tides; and he had covered the whole 
over with small stones, gravel, and a good thick 
layer of cement concrete, which made it correspond 
with the cement walk. 

The question of a winch was then taken up with 
Mr. Gregg and it was decided to construct a simple 
affair at the end of the boathouse opposite the 
large doors, where the boat would have to enter. 

Mr. Gregg suggested, in order to make the end 
of the building strong enough, that two upright 
posts be set up, well 
braced by being fas- 
tened to both floor 
and ceiling, and that 
the winch be attach- 
ed to them in a way 
that would be easy to 
work, as shown in Fig. 
19, room enough being 
left between the posts 
and the wall for the 
crank to turn without 
the hand of the oper- 
ator striking the Fig- l^- Winch and crank 

boards. The cylinder around which the rope 
should wind ought to be about six inches in dia- 




78 MECHANICS 

meter, and the crank or handle on the end, not less 
than fifteen or sixteen inches long. The longer the 
crank, the less force it would require to haul in 
the boat. If desired, a crank could be fitted to 
the other end of the cylinder so that two persons 
could work at one time, pulling in the weight. 

In the evening Mr. Gregg asked the boys and 
Jessie to visit his room, and he would try to explain 
the principle and advantages of the wheel and axle, 
as the winch they were to make was in a measure 
related to that principle. Mr. Gregg began by 
saying: ''The wheel and axle is merely a modifica- 
tion of the lever and consists of a couple of cylinders 
turning on a common axis, the larger cylinder is 
usually called the wheel, the lesser one the axle. 
This arrangement, which I draw on the blackboard 
herewith, forms a kind of lever of the first or second 
class. Considered as a lever, the fulcrum is at the 
common axis, while the arms of the lever are the 
radii of the wheel and of the axle. 

''The fulcrum is at C, the centre. The arm of 
the weight is W W, and the arm. of the power is 
A C. In Fig. 20 the arm of the power is the spoke 
of the wheel, while the arm of the weight is the 
radius of the axle. Fig. 19 shows the ordinary 
winch, often used in well-digging for hauling up 



f/H£EL 




Fig. 20. Wheel and axle 



BRIDGE AND BOAT WORK 79 

dirt and rock, and also for raising planks, shingles, 
rafters, and other light stuff, to the roofs and upper 
floors of buildings. Often it is made more powerful 
by adding spur or 
geared wheels to the 
end of the shaft, con- 
sisting of a pinion 
and a larger spurred 
wheel. The crank 
or handle is attach- 
ed to the pinion, 
and the power is increased according to the 
difference in diameters of the spur wheels. 
The machine is then called a ' crab ' and it is often 
used for lifting safes and other heavy weights to 
elevated situations. In Fig. 20 the length of the 
crank (in a straight line) is the arm of the power. 

" The mechanical advantage of the wheel and axle 
equals the ratio between the diameter of the wheel 

and of the axle. 

" It is not necessary that an 
entire wheel be present. In 
the case of the windlass and 
the capstan (Fig. 21), the 
Fig. 21. Capstan and hand bars power may be applied to a 

single arm or to a number of arms placed in the 




80 MECHANICS 

holes shown. The cable or rope on the barrel of 
the capstan is hauled in by turning the capstan on 
its axis, with handspikes or bars. The capstan is 
prevented from turning back by a pawl attached 
to its lower part, working in a circular ratchet on 
the base. 

**As an illustration of the lever action, and of 
work put into and got out of a machine, there is 

no better illustration 
than the ingenious 
contrivance termed 
the fusee (Fig. 22). 
In good watches 
and clocks, where 
the elastic force of a 
coiled spring is used to drive the works, the fusee 
compensates the gradually diminishing pull of the 
uncoiling spring. The driving of the works at 
a constant rate is the object for which a watch 
or clock is designed. This usually entails a 
constant resistance to be overcome, but since 
one of the most compact and convenient forms 
of mechanism into which mechanical force can 
be stored is that of the coiled spring, and since 
the very nature of the spring is such that its 
force decreases as it uncoils, we must employ some 




Fig. 22. Compensating fusee 



BRIDGE AND BOAT WORK 81 

compensating device between this variable driving 
force and the constant resistance. The fusee does 
this in a most accurate and complete manner. As 
the fusee to the right is to compensate for the loss of 
force of the spring as it uncoils itself, the chain 
is on the small diameter of the fusee when the watch 
is wound up, as the spring has then the greatest force. 

"In the differential, or Chinese windlass (Fig. 23), 
different parts of the cylinder have different diam- 
eters, the rope winding upon the larger and un- 
winding from the smaller. By one revolution the 
load is lifted a distance equal 
to the difference between the 
circumference of the two 
parts. 

*' There are many other 
contrivances and appliances 
of the wheel and axle for per- 
forming various services, but 
I think the examples I have shown you will be suffi- 
cient to enable you to make use of the device to 
perform any duty you may be called upon to at- 
tempt in ordinary life, but, should you enter 
professional life as civil, mechanical, naval, or mining 
engineer or architect, you will be obliged to pursue 
the study of these subjects further. 




Chinese winch and 
pulley 



82 MECHANICS 

"Before closing I may add a few problems for 
you to solve at your leisure by the application of 
the rules I have given you when describing the other 
mechanical powers. 

"The pilot wheel of a boat is 3 feet in diameter; 
the axle is 6 inches; the resistance of the rudder is 
240 pounds. What power applied to the wheel 
will move the rudder.^ Here the difference between 
the axle and wheel is 18 inches. 

"Four men are hoisting an anchor of 3,000 pounds' 
weight; the barrel of the capstan is 8 inches in 
diameter; the circle described by the handspikes is 
7 feet 6 inches in diameter. How great a pressure 
must each of the men exert? 

"With a capstan four men are raising a 1000- 
pound anchor; the barrel of the capstan is a foot 
in diameter; the handspikes used are 5 feet long; 
friction equals 10 per cent, of the weight. How much 
force must each man exert to raise the anchor? 

"The circumference of a wheel is 8 feet; that of 
its axle is 16 inches; the weight, including friction, 
is 85 pounds. How great a power will be required 
to raise it? 

"A power of 70 pounds on a wheel whose diameter 
is 10 feet balances 300 pounds on the axle. Give 
the diameter of the axle. 



BRIDGE AND BOAT WORK 83 

"An axle 10 inches in diameter fitted with a winch 
18 inches long is used to draw water from a well. 
How great a power will it require to raise a'cubic 
foot of water, which weighs 62 J^ pounds?" 

The first mail in the morning brought word that 
the whole of the partly prepared stuflf for the boat 
had been shipped by "fast freight," and that it 
would reach its destination in the course of a few 
days. The paper patterns, directions, and all 
necessary instructions for building would be mailed 
at once. 



IV 

MAKING A GASOLENE LAUNCH 

TWO or three days after Mr. Gregg had talked 
over the principles of the wheel and 
axle, with the children, Fred received 
notice that a consignment of wood-work was at 
the station awaiting his orders. Mr. Gregg made 
immediate arrangements with the railway people, 
and by the time he got home from his oflSce, the stuff 
was being unloaded by the boys, who carried it 
piece by piece into the workshop, each section 
being laid by itself in the order in which it was to 
be put in place in the boat. Printed instructions 
were in the equipment for laying the keel, setting 
up the frames, and even for taking the stuff out of 
the packages and putting it in heaps, so that it 
could be readily picked out when wanted for use. 

Each rib was numbered, and marked or stamped 
"right" or ''left," and all the pieces were cut oflf 
to the right length and to the right bevel or angle 
to suit the positions they were to occupy, as speci- 
fied in the printed instructions. This made the 

84 



MAKING A GASOLENE LAUNCH 85 

setting up an easy matter, requiring only care, 
patience, and a fair knowledge of the use of wood- 
working tools. That Fred possessed these qualities, 
was partly due to the training he had received in 
the technical school, and partly to his natural 
aptitude for picking up methods, ideas, and new 
applications. 

Fred, George, and Mr. Gregg himself, were much 
interested in the selection of the various materials, 
and when the plank that was to form the keel had 
been unpacked, George was anxious that it should 
be laid down on the bed that had been prepared for 
its reception. He was quite disappointed when he 
found it considerably shorter than he had expected 
the boat to be. It was explained to him, however, 
that the overhanging of the stern, and therefore 
shortening of the forefoot, or stem, necessitated 
the keel being shorter than the boat would be when 
measured over all on top. The keel was found to 
be a fine piece of tough oak, nicely dressed, made 
the proper shape at each end, bored and gained 
to receive the stern post, the stern ribs, and side 
stanchions. Everything was marked, and each 
timber was sized so that it would fit in place snugly 
without using a tool on it, except a hammer or mallet. 

At tea time George felt it diflScult to keep reason- 



86 MECHANICS 

ably quiet, he was so enthusiastic about the boat — 
much to the amusement of his father, who knew 
exactly how the boy felt. 

After tea, all walked to the boat house, and the 
father assisted Fred to set up the keel, which was 
in two pieces, halved together midway and well 
fastened with screws. The joint was painted with 




ICEEL AND KEELSON 



Fig. 24. Stem of launch 

a heavy coat of white lead and linseed oil paint, 
before being put together and screwed up. The 
keel is the lowest timber in a boat or ship, and it 
runs nearly the length of the craft. Sometimes 
there is a keelson placed on the top of the keel, 



MAKING A GASOLENE LAUNCH 87 

and the ribs of the boat, or stanchions, are made 
fast to that timber, as shown in the illustration, 
(Fig. 24,) in which the gains for the ribs or moulds are 
made. This portion of the boat was put together 
temporarily, so Fred had no difficulty in assembling 
the various pieces. The stem, keel, keelson, and 
deadwood were all made of oak, and looked strong. 
The keel and keelson were properly laid and adjusted, 
and after some explanations by Mr. Gregg the man- 
ner of setting up the ribs was thoroughly under- 
stood. Fred decided to telephone Walter Scott 
to come down next day, as it was Saturday, and 
help him to set up the skeleton. 

As the weather was getting warm, the whole 
family spent the evening on the veranda and George 
introduced the question of naming the boat. He 
suggested Red Bird, but this did not seem to 
take well, and several others were proposed but 
none seemed to suit everybody. Jessie sat quietly 
on the steps till asked by Fred what her choice 
would be. 

*'I would like it called after mamma, Caroline.'' 

"That's a good idea, Jessie," said her father, 
"and if the boys or your mother don't object, I 
think we'll settle on Caroline,'' 

Early next morning the boys were out watching 



88 MECHANICS 

for The Mocking-Bird, which very soon made its 
appearance. Fred and Walter tied the boat up to 
the new dock and went into the boat house, where 
the latter began to examine the boat stuff, and to 
explain the manner of setting it up and fastening 
it in place. 

Nick, who was on hand to help, did the heavy 
work, and helped to put up the stanchions. Walter 
seemed quite familiar with the work, and he and 
Fred soon had the boat so well in hand that it 
seemed to grow under their fingers. The ribs were 
easily selected, as they were tied together in pairs 
and numbered. They were then set in their places 
according to their numbers and were fastened to 
the keelson with the strong copper nails. All the 
nails required for the boat were of copper, because 
that metal is less likely to corrode than iron or steel. 

It was found necessary to brace the ribs in order 
to keep them in line. Thin pieces of lath were tacked 
on the tops to hold the ribs the proper distance apart, 
and longer and stronger strips of wood were used 
for bracing the boat sideways. These were nailed 
to the joints in the ceiling or high up on the walls 
of the boat house. 

At noon the boys had the skeleton of the boat well 
advanced, and to one standing in front of the bow. 




Copyright. 1911, by Underwood & Underwood, N. Y. 

Making a Motor Launch 



"All the Nails Required for the Boat Were of Copper, Because That Metal 
is Less Likely to Corrode Than Iron or Steel" 



MAKING A GASOLENE LAUNCH 89 

it presented an appearance like the sketch shown 
at Fig. 25. 

The launch might be called "carvel ribbon built," 
or nearly so, and it 
would have a dis- 
placement of 14 or 
15 hundred - weight 
when fairly loaded. 
This weight would 
bring her down to 

the third W. L., as ^'^' ^^- ^^^*^°° °^ launch - abeam 

shown in the end sketch. To load her to the fourth 
W. L., would give her a load far beyond these fig- 
ures. The sections had to be closely spaced, and 





JExamples of Lapstrake 
Fig. 26. Methods of sheathing 

the ribbons or slats let into the temporary section 
moulds before the outside boarding could be put on, 



90 MECHANICS 

the edges of the boarding being clinch fastened, as 
shown in the ribbon carvel, Fig. 26. Other styles of 
sheathing boats, as shown, are often used, but the 
Caroline was ''ribbon carvel." 

It is usual to lay off the sheer profile on a suit- 
able floor, and line in the rebate line, scarf of stem, 
deadwoods, fork timbers, etc., making thin moulds 
of each member to be lined oflF, sawn, and bolted 
together. The section moulds, from which the boat 
derives its shape, are also laid off, and the planking, 
%-in. thick, deducted when making them. 

The stem, of crooked oak, was 234 iii- thick by 
about 3 in., shaped as shown in Fig. 24. The fore 
deadwood was 23^^ in. thick, moulded about 3 in., 
and through-bolted to the stem and keel with ^- 
in. copper bolts; and the stern-post, 33^2 iii- thick, 
was wrought to shape, as shown. The centre line 
of the shaft, as shown, is subject to alteration, since 
different makes of motors have different sizes of 
propellers and flywheels. The fork timbers were 
let into the stern-post, and carried the transom, 
wrought out of a flitch of elm 33/^ in. thick. The 
planking, of Y^-in, cedar, was closely jointed and 
varnished, and secured to the ribbons. The tim- 
bers were of rock elm, J/g i^^- by J^ in., steamed 
and bent or sawn to shape, and through-fastened 



MAKING A GASOLENE LAUNCH 91 

at the top and bottom edges of the planking. These 
were spaced on l}/^-m. centres, with two clinch 
nails into the ribbons between them. Three or 
four solid floorings should be worked into the motor 
space; fitting of the motor bed thwartships gives 
great support to the boat. 

The thwarts were of oak, 8 in. wide and 1 in. 
thick, with the side seats, J^ in. thick, supported 
by turned legs of oak. The decks at each end 
should be of J^-in. oak or cherry reeded into 3 in. 
widths, and filled with marine glue. The covering 
board, %]/2 in- wide, with a nosing worked on the 
edges, and 3^ in. thick, was carried by a clamp or 
binding stake, 23^2 ^^' by ^ in., through-fastened 
at every timber. The knees were of oak, 1 in. 
thick, about 10 in. on the foot by about 3 in. at 
the head, and through-fastened. A breast hook 
2 in. thick should be fitted. The floor boards may 
be of ^-in. spruce, elm, or ash grating, as preferred. 
The centre of the motor was at No. 6 section, as 
indicated, the gasolene being stored in a strong tank 
under the forward deck, just high enough to feed 
by gravitation. After being cleaned off and sand- 
papered, a coat of good shellac varnish, may be 
followed, if desired, by three coats of best yacht 
varnish. The spacing of the sections was: No. 1, 



n MECHANICS 

from face to stem, 1 foot 2 in.; No. 2, from No. 1, 
is 1 ft. 2 in., the other sections to No. 11 each 1 ft. 
6 in.; No. 12 was 1 ft. 1 in. from No. 11 (see Fig. 25). 
The water-Hnes were 5 in. apart, and the buttock- 
lines, A and B, 1 ft. andl ft. 9 in. respectively from 
the middle line. 

The boys followed these directions, and with the 
help of the following table, managed to get the boat 
ready to varnish and finish up. The following table, 
which refers more particularly to the section shown 
in Fig. 25, shows the sheer lines, counting from 



TABLE OF OFFSETS 





S 

§ 


Section Numbers 


s 

II 




1 


2 


3 


4 


5 


6 


7 


8 


9 


10 


11 


12 




Sheer heights above 
L.W.L 

L.W.L. to rebate line... 

Half-breadths at gun- 
wale 

Half-breadths at 4 w.l. 

Half-breadths at 3 w.l. 

Half-breadths at l.w.l. 

Half-breadths at 1 w.l. 

Buttock A from l.w.l. 

Buttock B from l.w.l. 


^•1 

1 7 


1 6 

7 

2j 


1 5 

81 

1 3i 


1 4i 
9 

1 9^ 
1 8 
1 61 
1 31 

44 


1 3J 
9i 

2 11 
2 Oh 
1 11 
181 
1 3 

6i 

s 


1 2i 
9^ 

2 3i 
2 25 
2 2 
2 
1 6l 

7i 

3i 


1 2i 
9i 

2 41 
2 4 
2 3i 
2H 
1 8i 

8 
41 


1 2J 
10 

2 4i 

^^! 

2 n 

1 8i 
8 
41 


\n 

2 31 
2 3J 
2 21 
2 Of 
1 6i 
7J 
3J 


121 
101 

2 24 
2 11 
2 0- 
1 9 
1 O5 
5i 


1 3 
11 

2 

1 Hi 

1 9\ 

1 24 
51 

1 


1 31 

1 9^ 

1 7j 
8^ 

6 


14i 
161 

111 


1 6 



L W L (low water line). While all the work and 
calculations regarding the plan had been already 
done, Mr. Gregg, who had watched the work's prog- 



MAKING A GASOLENE LAUNCH 93 

ress for a week, thought they should know the 
principles on which the craft was being built, and 
therefore advised them to examine the illustration 
and table, so that they would have some knowl- 
edge of the science required to build a boat intelli- 
gently. Fred and George did this, and were helped 
along by Walter, who seemed to have mastered the 
subject pretty thoroughly. 

It was necessary, before installing the motor, 
that a foundation should be laid for it, so var- 
nishing and the final finish were left over until the 
engine and propeller should be put in and tried. 

The engine was brought to the boat house from 
Newark, and the expert, engaged by Mr. Gregg 
some time previous, came along with it, bringing 
such tools as he might want. He examined the bed 
for the engine, and saw that all was properly fastened 
and in good condition to place the engine and the 
propeller shaft. Mr. Watts (the machinist) laid 
off a line for the propeller shaft and with a long 
auger bored a hole from the engine bed through to 
the stern-post, large enough to permit the shaft 
of the propeller to revolve in it easily. A bearing, 
or "box," was adjusted to the stern-post in which 
the shaft ran, and the "box" was made water- 
tight to prevent any inflow. The propeller was 



94 MECH/VNICS 

made of bronze, had been nicely fitted to the shaft 
before it came, and had a set screw in its hub to 
hold it firmly on the shaft. The diameter of the 
propeller wheel measured 15 inches and it had two 
blades. The shaft and wheel being properly ad- 
justed, the next thing was to place the engine, 
which weighed about 200 lbs. The blocks and 
tackle used in taking down the old barn were 
rigged up to the ceiling by cutting a hole through 




Fig. 27. Starboard side of motor Fig. 28. Port side of motor 

the floor, laying a short timber across the joists, 
hitching a rope around the timber, and letting a 
loop hang down through the hole made in the floor. 
The hook of the upper block was attached to the 
loop, a sling was fastened to the engine, the whole 
was hoisted by Nick with the greatest ease, and the 



MAKING A GASOLENE LAUNCH 95 

machine dropped on its bed. As it did not lie quite 
level, it was raised again and held suspended until 
the bed was trued up, when it was permanently 
lowered into place and fastened down. Two views 
of the engine are shown in Figs. 27 and 28. 

In ''shop talk," the engine may be described as 
follows — Bore of cylinder 43^ in. Stroke 43^ in. 
Crank shaft 1^ in. Revolutions per minute 
from 60 to 750. Pro- 
peller shaft one inch. 
About 15 or 16 horse- 
power. A float-feed 
carburetor, Fig. 29, 
was installed at the 
same time. This car- 
buretor is an excel- 
lent one. It insures 

a regular supply of ^'^' ^^' Carburetor 

gasolene and air, in proper proportion, and prevents 
trouble when the motor is in use. The float guaran- 
tees an even level of gasolene in the float chamber 
at all times. The proper balance of the cork 
float closes the supply of gasolene automatically 
when it reaches the proper level. This prevents 
waste of fuel, every drop being thoroughly vaporized 
and mixed with the proper amount of air. The 




96 MECHANICS 

spraying nozzle is higher than the gasolene in the 
float chamber, and prevents the gasolene from 
getting into the engine, unless it is running. The 
throttle valve on the carburetor gives the operator 
the power to change instantly the speed, without 
changing the timer, and affords him absolute 
control of the engine. 

When all the machinery was in place, and the 
propeller attached, Mr. Watts told the boys that he 
would finish up the work of installing the next day, 
and would then run the engine "dry" for an hour 
or two, to get everything working nicely before 
declaring the Caroline ready for sea. 

It was just two weeks from the day the stuff 
arrived when the engine was finally installed. 

^'That's pretty quick work," declared Walter, 
"and if the boat were varnished, we could have 
her in the water in a couple of days." 

In the evening, as all the Greggs were seated on 
the veranda, Fred tried to explain to his father 
the installation of the engine, but he failed to 
make himself quite clear. 

Mr. Gregg said to him: "You seem to have 
grasped the theory of the matter, but I see you don't 
understand some important points, so I think a 
few suggestions may be of use to you. I will not 



MAKING A GASOLENE LAUNCH 97 

confine myself to marine motors altogether, as 
gasolene engines are used for many purposes, more 
and more every day. With regard to installing 
an engine in a boat, the first question is the bed, 
as you have seen in your own case, where your 
foundation is made good and solid. 

"Small engines may be supported upon a single 
cross piece at each end of the bed, but this method 
should be employed only for the smallest sizes. 

"The heaviest, and in most cases the hardest, 
pipe to fit up is the exhaust. It runs from the 
exhaust nozzle on the engine to the muffler and 
thence outboard. 

"The muffler is commonly placed in the stern 
with the outlet directly outboard. It may, how- 
ever, be in any convenient position, like under the 
seats in the standing room, and the piping led 
outboard. In any case, the piping for the exhaust 
should be as direct and as free from sharp bends as 
possible. 

"When the motor is near the middle of the boat, 
a good practice is to lead the exhaust pipe out 
through the bottom, and along it to a point near 
the stern, where it again enters the boat and connects 
with the muffler. The outlet from the muffler 
then leads directly outboard as before. This method, 



98 MECHANICS 

especially on a large cabin boat, avoids much 
loss of space and the disagreeable heat of the exhaust 
pipe. The surrounding water quickly cools the 
exhaust, reduces the pressure and makes the ex- 
haust almost noiseless. 

**The particular function of the muflBer is to 
afford a comparatively large space into which the 
exhaust may pass and expand, greatly reducing 
the pressure. The gas, under the reduced pressure, 
then passes out with little disturbance. The muffler 
need be of no particular shape, as long as the volume 
is sufficient. It is usually made of cast iron in 
the smaller sizes and of sheet iron in the larger. 
In many cases a long piece of rather large pipe will 
answer the same purpose. 

"The muffler may be dispensed with and much 
space saved by carrying the exhaust directly through 
the bottom of the boat and exhausting under water. 
Although this is a very convenient and many times 
satisfactory way, great care must be used or poor 
results will be obtained. When the exhaust leads 
directly out, a certain amount of pressure is used 
in displacing the water. This pressure is, of course, 
supplied by the piston and is a * back pressure,' 
retarding the piston and decreasing its power. 

*'A small expansion chamber or muffler should 



MAKING A GASOLENE LAUNCH 99 

be provided between the engine and the outlet, 
in order to break up the violent pulsations and make 
the flow fairly constant. Some form of shield 
should be fitted over the outer end of the exhaust 
pipe to guide the stream of the exhaust aft and 
prevent the water being forced into it by the move- 
ment of the boat. Several forms of these are on 
the market in the shape of brass castings which 
bolt on to the outside of the hull and have a thread 
on the inside to take the exhaust pipe. 

''When the under water exhaust is fitted, a pet 
cock should be put in the exhaust pipe near the 
engine. This is opened when the engine is stopped, 
thus preventing the water from being drawn up 
into the cylinders by the vacuum caused by the 
cooling of the gases in the pipe and cylinders. 

''The under water exhaust is a very neat and 
simple method, when correctly installed, as all 
noise and heat from the exhaust pipe are avoided. 
The exhaust may be considerably cooled and the 
noise reduced by dispersion. 

*'With regard to stationary engines, used for 
domestic or other purposes, any old place is con- 
sidered good enough to put them in. Now, this is 
one of the biggest and most expensive mistakes 
one can make, for as soon as some small screw gets 



100 MECHANICS 

loose in the far corner, the engine, salesman and 
manufacturer are unjustly blamed, simply because 
the present owner has not left enough room to make 
the small adjustments necessary in every engine 
and piece of machinery. Therefore, it pays always 
to install the engine in a light, dry place, easy of 
access and with suflScient space all round to enable 
all parts to be reached and to give plenty of room 
for turning the fly wheels in starting. Whenever 
possible, place the engine on the ground floor. 
On an upper floor, the necessary provision should 
be made to avoid vibration; if installed in the 
basement, place it in the best light. 

*' Without a good foundation, an engine may be 
expected to give more or less trouble from vibration, 
since it is subjected to forces, suddenly and repeatedly 
exerted, which produce violent reactions. Care 
should be taken to excavate down to good soil and 
to line the bottom with a substantial thickness 
of concrete in order to form a single mass of arti- 
ficial stone. The foundations may then be built 
up of either concrete, brick, or stone. Anchor 
plates should be extended to the bottom of the 
masonry and fastened so as to prevent turning 
while the nuts are being screwed up. Place gas 
pipes or tubes with an inside diameter twice the 



MAKING A GASOLENE LAUNCH 101 

diameter of the bolts around them, while the founda- 
tion is being built; this allows the bolts to be 
adjusted, and any variations between the tubes 
may be filled with thin cement after the engine is 
set. 

"The top of the foundation should be finished 
perfectly flat and level with a dressing of cement, 
and after this is thoroughly dry the engine may be 
placed in position. When bolting down the engine, 
it is better to draw each bolt down a little at a 
time until all are tight and thus avoid straining 
the engine crank. After the nuts are drawn tight, 
if the crank turns unreasonably hard without 
loosening the main bearing caps, it may indicate 
an uneven foundation, which is a strain in the engine 
bed casting. 

"When setting up large engines, for farm or 
other purposes, especial care must be taken to 
avoid straining the bed castings. Foundations 
hung from an upper floor, or built upon it, should 
be placed as close to the wall as possible. For the 
smaller sizes of engines it is a good plan to lay 
wooden beams on top of the foundations and then 
to place the engine on top of them so that when 
the frame is bolted down it beds itself into the 
timber. The timber cap often saves an annoying 



10« MECHANICS 

vibration when it can be overcome in no other way. 
"All the connections should be as short and as 
free from turns as possible, and no mistake can be 
made by having plenty of unions, so as to discon- 
nect with ease. The gasolene tank should be set 
as near the engine as is convenient, with the top 
of the tank, preferably, not more than a foot or two 
'below the base of the engine. In cases where the 
gasolene tank must be set from forty to fifty feet 
away, it is necessary to place a check valve in the 
suction pipe near the tank. Both suction and 
overflow pipes must have a gradual rise all the way 
from the tank to the pump and should be as straight 
as possible to avoid the air traps, which prevent a 
steady flow of gasolene. It is most essential to 
clean thoroughly all pipes and fittings before they 
are put together, by hammering lightly to loosen any 
scale and washing out with gasolene, as solid matter 
of this nature may be responsible for some of the 
simple, but hard-to-get-at troubles common to 
gasolene engines. 

"Shellac is best for joints in gasolene piping, but 
when this cannot be obtained common laundry 
soap will answer the purpose just about as well. 
Remember, also, that gasolene is a rubber solvent, 
and should never be applied to joints where rubber 



MAKING A GASOLENE LAUNCH 103 

is used. In some cases it will be found advisable 
to use gravity feed instead of a pump, except in 
the case of the tank, which must be so arranged 
that its lowest point is slightly above the generator 
valve. 

"The exhaust pipe must be of full size, free from 
turns and short as possible, since the shorter it is 
the more economically the engine will run. It 
will be found advisable to place the muffler and 
exhaust piping away from combustible material, 
and never to turn the exhaust into any chimney or 
flue. 

"There are two general methods of supplying the 
water, the first being that of the cooling tank com- 
monly used with small engines. For convenience 
in piping, the tank should be slightly elevated, 
and both pipes, having as few bends as possible, 
should slope from the tank to the engine, a valve 
being placed in the bottom pipe near the tank. 
By using a circulating pump, fitted to the engine 
or shaft, water may be used from an underground 
cistern or tank. 

"The other method is to use a continuous cooling 
stream from water-works' or other source. When 
city water is used, it is a good plan to have a break 
and funnel inserted in the drain pipe so that the 



104 MECHANICS 

current of water flowing through the cylinder 
jacket may be seen. For making joints in 
water pipes, either thick lead or graphite may be 
used with almost equal success. It may be well 
to place particular emphasis on the fact that it will 
pay to get into the habit of always shutting off the 
water at the tank and draining the cylinder every 
time the engine is stopped — not necessary in sum- 
mer, but absolutely essential in winter — as a fair 
percentage of gasolene users know to their cost. 

"The greatest care must be employed in using 
and handling gasolene, as it is dangerous and highly 
explosive. It has been known to explode when 
20 or 30 feet from light, the vapours having reached 
the fire in the way of a gas, igniting and firing the 
liquid. And, now, right here, let me impress on you 
this warning; never handle gasolene near a fire or 
light under any circumstances, and be very careful 
with it under all conditions. 

'* Fortunately, there are few accidents resulting 
from gasolene, when we consider the large amount 
used since it has become almost a universal fuel 
for engines, and it is also used largely for 
domestic heating and lighting. 

''It is a product of petroleum, of which in its crude 
form about 76 per cent, is turned into kerosene, 11 



MAKING A GASOLENE LAUNCH 105 

per cent, into gasolene, 3 per cent, into lubricating 
oils, and the balance into vaselines, paraffine, coke 
and so forth. 

*' Different petroleums produce different propor- 
tions of the various products, some of them being 
considerably richer in gasolene than 11 per cent. 

"Gasolene is usually designated according to its 
specific gravity by an arbitrary measure, known as 
Baume's hydrometer scale. This designation is 
in degrees, the most common gasolene ranging be- 
tween 65 degrees and 85 degrees, and the average 
being 70 degrees, the usual density used in engines. 

"You will find it somewhat diflicult at first to 
start up your engine when you wish to, so I will 
give you a few hints to show how this difficulty may 
often be overcome. 

"There is always a reason why a gas engine re- 
fuses to obey the behest of its driver. 

"In the first place, see that the compression is 
right and the admission valve so tight that it will 
admit only enough of the mixture (gasolene and air) 
to make a charge that will take fire from the sparker 
and move the piston forward. Next see that the 
sparker is clean, that it will make a bright spark 
at white heat when the contact is broken, and at 
the right time. 'In time' means to go if everything 



106 MECHANICS 

else is right, and 'out of time' means not to go even 
when everything else is right. 

"The valve of the engine must be kept well 
ground down with emery and oil so as to preclude 
the possibility of a leak, as one would very seriously 
weaken the power of the engine even after it had 
started. The spark must be made when the con- 
necting rod of the engine is on the 'up stroke,' 
with the crank shaft about three inches below the 
horizontal line of the centre of the index, and herein 
lies the whole secret of the greatest efficiency from 
the least amount of gasolene. As there is an inter- 
val of time after the spark is made until it ignites 
the charge, it is very evident that the movement 
of the machinery continues and the moment of 
ignition should take place when the compression 
is greatest. This will be when the piston is on its 
farthest 'in stroke,' i. e,, in perfect line with the 
centre of the cylinder. But if the charge be ignited 
at this point the engine will not develop the greatest 
power, as the interval spoken of will elapse and the 
piston will have started on its 'out stroke', thereby 
not getting its full force of the expansive gases 
liberated by combustion of the air and gasolene. 

"So you will readily see that you must allow for 
the interval spoken of, if you would get full returns 



MAKING A GASOLENE LAUNCH 107 

for the energy used in propelling the motor. I 
have tried to make this plain, and I hope my efforts 
will help you out with your engine, either in starting 
or developing the power at which it is rated." 

It was not yet late, so the boys took down from 
the book shelf a code of yacht flag signals, and found 
the following : 

'* There are no hard and fast rules regarding 
shapes and colours of yacht bunting, but the fol- 
lowing are generally accepted by the prominent 
clubs in the United States and in foreign countries. 

1. The "pennant" (a triangular shaped flag) 
is used for the club burgee. 

2. The "shallow tail" is adopted for the private 
signal. 

3. The rectangular flag is chiefly used for a flag 
oflScer's signal. 

4. The shape, consequently, at once denotes 
whether a flag is that of a club, a flag officer, or a 
member. 

5. The majority of flag officers' signals are 
coloured: Blue for commodore, red for vice-com- 
modore, and white for rear-commodore. 

6. The international code of signals enables 
yachts to communicate with each other, and is also 
used for dressing ship. 



108 MECHANICS 

The ensign should be flown from the peak of the 
main-sail on a sailing yacht, when under way, and 
from a stern flag pole when moored. 

On a yawl, it should be hoisted at the mizzen 
truck. 

vOn a steamer, launch, or dinghy, it should be 
flown from a stern flag pole, when under way or 
at anchor. 

Club Burgee, — The burgee should measure 
in length about one-half inch for each foot of height 
of truck from the water; width to be two-thirds 
of the length. Private signals may be smaller. 
^. The burgee should be flown from the mast-head 
or truck of a cutter, sloop, or cat-rigged yacht, the 
main truck of a yawl, the fore truck of a schooner 
and steamer, and from the bow pole of a launch 
or dinghy. 

Flag officers' and private signals should be flown 
from the truck of a cutter, sloop, or cat-rigged yacht, 
the main truck of a schooner, yawl, or steamer, 
and from the bow pole of a launch or dinghy. 

The following flags are not considered as colours: 

Night Pennant {Jblue) . — Is hoisted at the main 
truck from sundown to 8 a. m.; also occasionally 
used as a tell-tale when racing or sailing. 

Owner^s Absent Flag {blue rectangular) . — Is flown 



MAKING A GASOLENE LAUNCH 109 

from the main starboard spreader when yacht is 
at anchor only. It denotes owner is not on board, 
but should never be flown when under way. 

Owner^s Meal Flag {white rectangular) . — Is flown 
from the main starboard spreader, and denotes 
the owner is at meals — boarding a yacht when 
this flag is flying is considered bad form. 

Crew Meal Flag {red triangular) , — Is flown from 
the foreport spreader on schooners and main- 
port spreader on single-masted yachts. This de- 
notes that the crew is at meals. ^^ V 

The Ensign, — Displayed on a vessel indicates 
distress and want of assistance. 

Flag ''B," of the International Code of Signals, 
is used for a protest flag, and is conspicuously 
displayed in the rigging of a yacht protesting during 
a race. 

A yacht, on withdrawing from any race, should 
at once lower its racing colours, and allow yachts 
still competing the right of way. ^; 

This code was studied by the boys until both of 
them thoroughly understood its full meaning, and 
George became so enthusiastic over it that he 
exclaimed: "Fred, I am going to be an admiral of 
the navy!" 



A TALK ABOUT ENGINES 

MR. WATTS was early at the Gregg resi- 
dence next day, and busied himself prepar- 
ing the engine to start up. A big tub was 
taken to the boat house filled with water by a hose 
attached to the suction pipe, and dropped into the 
water. This was a mystery to George, who inquired 
about the use of the water and the other attachments. 
It was explained to him, that outside the cylinder 
there was a hollow space, called the "water jacket," 
extending over the top of the cylinder, and this 
had to be kept full of cold water by continual 
circulation. It was pumped in by the engine and 
forced out by the same means, a simple contrivance 
being arranged for the purpose. This circulation 
of water is necessary to keep the inside of the 
cylinder cool, otherwise the walls would soon be- 
come red hot, on account of the rapid explosions 
of gas and air employed in the cylinder to keep the 
piston moving to and fro. 

George seemed to grasp the idea thoroughly. 

110 



A TALK ABOUT ENGINES 111 

Mr. Watts also explained the use of the carburetor, 
the spark coil, the battery, and the method of con- 
tact to produce a spark at the proper moment. 
After some screwing of bolts, adjusting the piston, 
and trying the valves, the tank in the carburetor 
was supplied with gasolene and Mr. Watts tried the 
engine for a few revolutions, as gently as it could 
be done. It was a little stiff at first, some of the 
connections fitting too tight, and the piston, being 
new and harsh, did not work smoothly. By the 
judicious use of good lubricating oil and a few turns 
of some of the nuts on the bolts, a little more freedom 
was given to the machine and the starting was easy 
and smooth. George and Jessie were delighted 
with the rapid movement of the machine, the buzz 
of the propeller, and particularly interested in the 
movement of the water in the tub. 

Mr. Watts allowed the engine to run quite a little 
while, and arranged the exhaust so as to beat regu- 
larly and to "pop! pop!" as little as possible. He 
then called Fred into the boat and taught him how 
to run the machine, arrange the contact breaker, 
and regulate the feeding of fuel. The engine was 
stopped to cool and to be examined again by Mr. 
Watts, who pronounced it all right. Mr. Gregg, 
who had arrived just before the engine was stopped, 



112 MECHANICS 

examined all its parts and watched it work for a 
minute or so. 

Fred arranged his pots and brushes, and he and 
George went to work varnishing, so that before 
sunset the Caroline looked quite smart and 
trim. The boys were very careful in applying the 
varnish to put it on light and thin so as not to let 
the coats lap over one another as they went along. 
They finished each "streak" from end to end, before 
starting on the next, and following this method they 
obtained a nice, even surface. The varnish did not 
look *' blotchy" or patched, as it would have done 
had the ends of the varnish lapped. To avoid 
*' lapping" is one of the most essential operations 
in varnishing, when a nice piece of work is desired. 

It was decided to give the little craft two more 
coats of shellac varnish before launching her, and 
the following spring to give her a good coat of marine 
varnish. Mr. Gregg thought that in another week, 
say the following Wednesday, the Caroline might 
be launched with safety, as the varnish would 
get dry and hard, and the inside paint would also 
be hard enough. Jessie and the boys were given 
permission to invite a few friends each to the boat 
launching, and were promised suitable refreshments 
to be served on the new grounds, if the weather was 




Copyright, 1911, by Underwood & Underwood, N. Y. 

Finishing the Motor Launch 



'To Avoid 'Lapping' is One of the Most Essential Operations in Varnishing' 



A TALK ABOUT ENGINES 113 

favourable. Fred asked his father if he could not 
build up some temporary picnic tables and seats 
for the occasion, as there was plenty of material 
still left unused from the old barn stuff. Permis- 
sion was granted, and after counting up the number 
that would probably be present, it was found that 
three tables, each about fifteen feet long, with neces- 
sary seats, would give ample room for the accommo- 
dation of the proposed guests, with a good allow- 
ance for overflow. 

Just then the whistle of a small steam tug, that 
often plied on the river, gave warning of her ap- 
proach ; and all went down to the river edge to watch 
her pass and to see what effect her ''wash" would 
have on the new pier and the boat house "skid" 
or slides. She came up stream rapidly against 
the tide — which was on the ebb — and there was 
a considerable "wash" from her wheel, but it struck 
the bank, the pier, and the "skids" without doing 
the least harm or giving any evidence that trouble 
would result from any reasonable wash. The little 
steamer's exhaust, as she passed, made quite a noise 
and Jessie was somewhat puzzled at this, as the 
exhaust from the gas engine of the Caroline 
only made a plaintive puff in comparison. Her 
father promised to explain the reason after tea. 



114 MECHANICS 

Returning to the boat house, George suggested 
that the name of the boat be painted on both sides 
of the bow, in large letters, but Mr. Gregg and Fred, 
thought it better to have ''Caroline" placed on 
the second streaks of sheathing, in gold, the letters 
to be not more than two inches over all. This was 
agreed upon, and a young artist, who was a near 
neighbour, was suggested as the person to do the 
work. 

After tea, Jessie and the boys followed their 
father into the den, where Mr. Gregg gave the 
children a brief history of the steam engine, as far 
back as known, commencing with the 
Colipyle, the invention of Hero of 
Alexandria about 130 B.C. An illus- 
tration of this is shown in Fig. 30. 
It was simply a pot or boiler, partly 
filled with water, the lid or cover being 
Fig. 30. Hero's fastened down tightly. On the top of 
steam engine ^j^jg ^^^ attached a hollow bcut tube 

having a tap fitted to it, which supported and 
communicated with a hollow metal ball hung on 
another tube or bearing on the other side in such a 
manner that the ball could revolve easily. Attached 
to this hollow ball or sphere were four other hollow 
tubes, so fastened as to project from the surface two 




A TALK ABOUT ENGINES 115 

or three inches, and these were bent at their outer 
end, as shown in the illustration. These tubes were 
of course attached and bent in a direction at right 
angles to the axis of rotation. The tap leading to 
the hollow ball, when turned open, allowed the steam 
from the boiler to rush into the ball and fill it up. 
If it was closed entirely, the ball would remain still, 
but the steam exerting an equal pressure on all 
points of the inner surface, and finding the openings, 
escaped through with a rush and noise as it condensed 
in the air, which it pressed against, causing the ball 
to revolve in an opposite direction to the outflow 
of steam. This Hero engine or Colipyle, was doubt- 
less the beginning of steam motors, but during the 
2,000 or more years since Hero's toy engine was in- 
vented, great strides have been made toward bring- 
ing the steam engine to its present efficiency. 

*'But I do not intend," said Mr. Gregg, ''to give 
a history of the growth and development of the 
machine, at this time. There are numerous works 
on the subject, obtainable in any fairly-equipped 
library." 

Steam, as everybody knows, is generated by heat 
being applied to a closed metal kettle or boiler con- 
taining water. This boiler must be strong and 
properly arranged so as to admit more water — 



116 MECHANICS 

which is usually injected with a force pump — 
and it must have an outlet for the release of the 
steam to the cylinder of the engine. Generally, 
there is a small dome on the top of the boiler, called 
the "steam dome," and to this the steam outflow 
pipe is attached. The actual use of this dome is to 
hold a volume of steam that will remain unmixed 
with water, as it is placed considerably above water 
level. On the top of the dome there is an automatic 
arrangement called a "safety valve," so that when 
there is too much pressure of steam in the boiler, 
it will open and allow the over-pressure to escape, 
and thus prevent the boiler from exploding or being 
over strained. This valve is controlled by a simple 
device, somewhat similar to a steelyard. A movable 
weight is arranged to slide on a long arm which is 
loosely fixed to the valve flange by a bolt and nut, 
and extends some distance past the seat of the valve. 
The arm or lever has an iron pin attached to it 
directly over the valve seat, which holds down the 
valve and keeps the steam from escaping. The 
movable weight on the arm is adjusted so as to 
regulate the pressure on the valve. When there is 
too great a pressure, the valve forces up the lever, 
and at the same time opens a passage for the extra 
pressure of steam to escape. There are several 



A TALK ABOUT ENGINES 117 

other contrivances for relieving the boiler of over 
stress, but the one described, or rather the principle 
on which it is built, is most in use on this country. 
There are many kinds of boilers, or steam generators, 
but the best, and very likely the strongest, are those 
employed on our first-class railway locomotives. 
These are frequently 
under a pressure of 200 
or more pounds to 
the square inch, which 
seems an enormous load 
for a hollow shell to 
carry, yet, so near per- 
fection are they, we 
rarely hear of a locomo- 
tive boiler explosion. 
As there are many 
kinds of boilers, so also 
are there many kinds of ^^^ ^^- ^^'^^^ "^^^^^"^ ^^^ p^'^^° 
steam engines, but all of these latter, with very few 
exceptions, have a cylinder and piston for converting 
the force of the steam into useful and effective motion. 
The manner of using this force and keeping it under 
proper control is somewhat complex and difficult 
to describe briefly, without elaborate diagrams, but 
Mr. Gregg explained, in his own way, how the 




118 MECHANICS 

great force was converted into motion. On the 
blackboard he drew a rough diagram of a cylinder 
and valve or steam-chest, with piston and slide- 
valve, about as shown in Fig. 31, which gives a 
longitudinal section of the whole arrangement. 
Here we see near each end, the opening of a double 
conduit aa, made in the thickness of the side; 
these are the openings by which the steam 
comes alternately to work on one end, then on the 
other, of the piston. These are called the steam- 
ports. These two open outward on a well-polished 
surface, and between the two a third opening, E, is 
seen, which serves to let the steam escape when it has 
done its work, and is called for that reason the ex- 
haust port. C is the pipe by which the steam gains 
access to the open air or to the condenser, where it 
parts with its elastic force. 

Here is shown by what contrivance the distribu- 
tion is eflfected, consisting, as it does, of two partial 
operations ; the admission of the steam and its escape, 
which must be repeated twice to obtain a complete 
phase of the to-and-fro movement of the slide-valve. 
There are various methods employed according 
to different engines — but the first described is the 
one represented by the illustration. 

In the valve chest, BB, is seen a prismatic box. 



A TALK ABOUT ENGINES 119 

open on one side, called the slide-valve, and this 
is applied by its open face to the well-polished 
plane on which, as mentioned before, the three 
ports open. The space BB, is called the valve or 
steam chest. The steam coming from the boiler 
by the pipe C spreads out freely in it, but the 
inside of the slide-valve, on the contrary, is always 




Fig. 32, Steam valves — different positions 

closed to the entering steam, though constantly 
in communication with the escape pipe and also 
with first one then the other of the entrances to 
the cylinder. Lastly, the movement of the slide- 
valve is produced by the engine itself, aided by a rod 
and an eccentric fixed to the shaft of the fly- 
wheel. 



120 MECHANICS 

By following the successive and alternating mo- 
tions of the slide-valve, as represented in Fig. 32, 
we can easily comprehend the different phases of 
the distribution of the steam. 

This is the machinery for the distribution of 
steam generally. There are other engines, such as 
rotary and oscillating, that are supplied by other 
contrivances, but most of these have fallen, or are 
fast falling into disuse, as they are not so satisfac- 
tory as the ordinary slide-valve. It will be seen 
upon examination of the sketch, shown in Fig. 32, 
how the steam enters and leaves the cylinder and 
the position of the piston under the various positions 
of the valves. The arrows show the direction of 
the slide, also the direction of the piston and its 
position when the slide covers the ports X, or leaves 
them open, or partly so. The ports for egress 
or ingress are shown at X, the slide-valve at V, and 
the cylinder at C. When the piston is near one end 
of the cylinder, the steam is admitted and forces 
the piston in the opposite direction, while the valve 
is so arranged that when the piston starts in that 
other direction, it begins to open the port at the 
other end of the cylinder through which the 
exhausted steam escapes. This makes the noise 
Jessie asked her father about. There are some 



A TALK ABOUT ENGINES 121 

engines so devised that the exhaust is made to assist 
in driving another engine. 

Of course, there are many kinds of steam engines, 
but all are run on the same principle, or nearly so. 
As you know, steam is generated in boilers by fire 
being applied to the outside and the water made 
hot enough to raise steam. A steam engine is said 
to be externally heated, while gas, oil, and other 
similar engines are internally heated, because 
instead of the steam driving the piston, the gas, 
oil, or other explosive matter is admitted into the 
clearance or space between the piston and the end 
of the cylinder, where it is exploded by an electric 
spark from a battery provided for the purpose, 
and this is called the ''ignition." The explosion 
causes the gas and air in the cylinder to expand, 
bringing a great pressure on the piston, forcing 
it to move toward the other end of the cylinder, 
and making the whole machine move. One great 
advantage of employing a gas engine is that no 
boiler is required, a very important matter, as 
boilers take up a great deal of space. The coal 
or wood necessary to keep up steam also takes space 
that could be used for other purposes, all of which 
make the use of steam objectionable when ,it is 
possible to employ suitable gas engines. Besides, 



122 MECHANICS 

the make-up of a steam engine is of such a character 
that it is very expensive, while the first cost of 
gas engines is much lower. 

All gas, oil, or other explosive engines are in- 
ternal heaters, because the heat is generated in the 
cylinder at each explosion, and this is one of the 
main features that distinguishes the gas from the 
steam engine. Of course, there are many attach- 
ments and connections to steam and gas engines 
that would take too long to describe, and in a great 
measure be unnecessary. A few items may prove 
both useful and profitable and it is well to know 
firstly: How to estimate the horse-power of an 
engine. 

When steam engines were first introduced they 
were largely used to take the place of the horses 
previously employed for raising water from mines. 
Naturally people inquired, when buying an engine, 
what amount of work it would perform as compared 
with horses. The earliest engine builders found 
themselves very much at a loss to answer this 
question so they had to ascertain how much a horse 
could do. 

The most powerful draught horses and the best 
of any then known were the London brewers' horses. 
These, it was ascertained, were able to travel at 



A TALK ABOUT ENGINES 123 

the rate of two and a half miles per hour and work 
eight hours per day. The duty, in this case, was 
hoisting a load of 150 pounds out of a mine shaft 
by means of a cable. When a horse moves two and 
a half miles per hour, he travels 220 feet in a minute, 
and, of course, at the speed named, the 150-pound 
load would be raised vertically that distance. That 
is equal to 300 pounds lifted 110 feet per minute, 
or, 3,000 pounds lifted 11 feet or 33,000 pounds lifted 
one foot high in one minute. That is the standard of 
horse-power, as we all know. It is much more, 
however, than the average horse can do, and there- 
fore the builders were conJBdent that the engines 
would take the place of fully as many horses as the 
horse-power would indicate that they should. 

Of course, 33,000 pounds lifted 1 foot per minute 
is much more convenient for calculation than 150 
pounds lifted 220 feet, and therefore the former 
rate has been adopted. The amount of work, or 
number of "'foot-pounds," is the same in either case. 
A foot-pound represents the amount of power re- 
quired to lift one pound one foot high. To find the 
number of horse-power in any engine, we multiply 
the area of the piston by the average pressure per 
square inch upon it; multiply this result by the 
distance which the piston travels per minute in 



lU MECHANICS 

feet and the result is the number of foot-pounds 
per minute which the engine can raise. Divide by 
33,000 and the result will be the number of horse- 
power. The number of feet per minute travelled 
by the piston is twice the number of strokes per 
minute multiplied by the length of the stroke. 
This gives the amount of horse-power sufficiently 
accurate for all practical purposes. 

It necessarily takes time to do work, but the 
amount of work done has nothing whatever to do 
with the time taken to do it. 

If a man, weighing 150 pounds, walks up the 900 
steps leading to the highest attainable level in the 
Washington Monument, 500 feet high, he does work 
against gravity equal to 75,000 foot-pounds, irre- 
spective of the time taken in the ascent. Then the 
work done in a given time, divided by the time, 
is called the power of activity. 

Power is the time rate of doing work. In the 
English gravitational system, the unit of power is 
the horse-power (H. P.); it is the rate of doing work 
equal to 33,000 foot-pounds a minute, or 550 foot- 
pounds a second. 

In the centimetre-gramme-second (C.G.S.) sys- 
tem (in which the unit is 1 gramme moving at 
the rate of 1 cm. a second), the unit of power is 



A TALK ABOUT ENGINES 125 

the watt. It equals work done at the rate of one 
joule (10,000,000 ergs) a second. 

One horse-power is equivalent to 746 watts. 

A kilowatt (K.W.) is 1,000 watts. 

It is therefore nearly 1}/^ horse-power. 

To convert kilowatts into horse-power add one- 
third; to convert horse-power into kilowatts, sub- 
tract one-fourth. 

For example, 60 K. W. equals 80 H. P. and 100 
H. P. equals 75 K.W. 

The expression foot-pound is in general use among 
English-speaking engineers, and as explained it 
is the unit of work done by a force of one pound 
working through a distance of one foot. It is not 
a fixed standard of measurement, since the weight 
of a pound is not the same in all heights above sea 
level, and on this ground it is open to objection. 
It is the nearest constant, however, we have yet 
discovered, hence its general adoption. 

*'Dry steam" is the steam in which no condensa- 
tion is visible, and it may generally be obtained at 
a 10-pound pressure per inch, but no exact dividing 
line of pressure can be defined between dry steam 
and wet. If care is taken in covering pipes and 
cylinders, to prevent condensation, a pressure of 
10 pounds should make steam as dry as gas, and if 



126 MECHANICS 

the steam pipe is carried through a good, hot fire 
at some point, the fire will superheat the steam and 
render it more dry. Wet steam, of course, is steam 
that can be seen, through having been more or less 
condensed by contact with air or cold. There can be 
no steam without heat, but steam does not require 
as much heat as is generally supposed. Suppose we 
take one pound of water at 32 degrees Fahrenheit 
and apply a fixed and known quantity of heat until 
it boils; we will assume that it takes 20 minutes, and 
we have supplied the water 180 heat units, which, 
added to the 32 contained in the water at the start, 
makes 212 degrees Fahrenheit or heat units, and is 
the sensible heat of steam at atmospheric pressure. 
Now let us continue the same quantity of heat per 
minute until all the water has evaporated into-steam, 
and we will then find that it has taken five and one- 
third times as long, or 10 minutes to do this work. 
Consequently we have used five and one-third times 
180 or 960 heat units; or, to be exact, 966 heat units. 
Now the temperature of the steam is the same 
as the water from which it has evaporated, or 212 
degrees Fahrenheit, and this 966 heat units is the 
latent heat of steam at atmospheric pressure. All 
steam has a sensible heat corresponding with the 
temperature of the water it has evaporated from. 



A TALK ABOUT ENGINES 127 

If you boil water under a pressure of five atmos- 
pheres, or 75 pounds pressure, the sensible heat is 306 
degrees Fahrenheit, the boiling point at that pressure, 
but the latent heat has decreased by the same number 
of heat units that the boiling point increased, so 
the total is the same in all cases. In the first in- 
stance we have 212 degrees minus 32, plus 966, or 
1,146; and in the second 306 degrees minus 32, plus 
872 or, 1,146 heat units. This may be considered 
a fair description of latent heat. 

The most useful quality of steam yet discovered 
is its power of expansion. It follows what is known 
as Marriott's Law of Expanding Gases, which means 
one-half the pressure double the volume. So if 
we let steam into an engine cylinder, at 80 pounds' 
pressure, and cut it off at one-fourth stroke, it is 
at 80 pounds up to the point of cut-off. At one-half 
stroke, because it has doubled its volume, it is 
reduced to one-half pressure, or 40 pounds; while 
at three-fourths stroke the volume has trebled and 
the pressure has dropped to nearly 27 pounds, and 
this is why it is economical to run engines that use 
steam expansively. Steam at 27 pounds' pressure 
is very much cooler than steam at 80 pounds, and 
this difference in temperature has been converted 
into mechanical work by our steam (heat) engine. 



128 MECHANICS 

There are many other peculiarities about steam 
and steam engines that a young boy should know, 
and the information can readily be obtained from 
books in any good library. 

The steam turbine, of which so much has been 
heard lately, is not constructed like an ordinary 
steam engine with cylinder, slide-valve and other 
attachments; but more like the Hero engine, with 
this difference that the steam jet or jets act on a 
wheel having vanes or blades, the expansion pro- 
ducing a velocity which rotates the wheel containing 
the vanes. A modern turbine, of the Parsons 
type, such as are employed on the great Atlantic 
steamers, is a tremendously high speed engine. 
It does not derive its power from the static force 
of steam expanding behind a piston, as in a recip- 
rocating engine. In this case the expanding steam 
produces kinetic energy of the steam particles, 
which receive a high velocity by virtue of the ex- 
pansion, and, acting upon the vanes of a wheel, 
force it around at a high speed of rotation in the 
same manner as a stream of water rotates a water- 
wheel. The expansion produces velocity in a jet 
of steam, and this is the main difference between the 
ordinary engine and the modern steam turbine. 

Among gas and internal explosion engines there 



A TALK ABOUT ENGINES 129 

exist some differences, both in construction and in 
the manner of supplying fuel. The gas-producing 
engine may be considered the better class, though 
it has not as yet gained the popularity of the gaso- 
lene one. The gas by which this style of engine 
is operated is produced by a special process, namely, 
by passing air and steam through a fire of hot coals. 
After generation the gas passes over a flash- boiler 
and a portion of its great heat is withdrawn, thus 
permitting it to enter a scrubber — a cylinder filled 
with coke and saw-dust — while fairly cool. In 
passing over the flash-boiler the great heat raises 
all the steam necessary for the production of gas 
required in the operation of the engine and plant. 
In passing through the scrubber the gas is not only 
cooled, but is freed from particles of suspended 
matter, the coke removing the heavier particles, and 
the sawdust, the tar, or any other volatile matter 
that may be left. 

One of the most important requirements in a 
gas-producer is that it shall be adapted to the work 
it has to do. Its construction should be compact 
and simple, so as to permit the easy removal of worn 
out parts. The feeding device should be such as 
to secure a uniform distribution of fuel. 

The blast should be so introduced as to bum out 



130 MECHANICS 

all the carbon in the ash zone, and yet not produce 
localized combustion along the walls. The con- 
struction should permit the easy removal of ashes, 
and render the machine safe, while the entire proc- 
ess of gasification should be clean. The radiation 
loss should be low, and the producer must be made 
eflScient to insure satisfaction. 

It should be borne in mind that because of the 
presence of carbon monoxide, producer gas will 
always be more or less poisonous. The carbon 
monoxide has a specific toxic effect on the human 
system, and when inhaled enters into direct combina- 
tion with the blood, and brings about very dangerous 
effects. 

As water is always required for cooling purposes 
when running a gasolene engine, it is well to know 
about how much will be required. One authority 
says: ''The quantity of water required at the or- 
dinary temperature of 60 degrees F. inlet and 150 
degrees outlet, to keep the cylinder of gas engines 
cool is 4.5 to 5 gallons per indicated horse-power- 
hour. The jacket pipe should be from 1 to 2 inches 
diameter for engines up to 20 horse-power, while for 
larger engines the sizes are generally 2 to 3 inches 
for the inlet and 2.5 to 3.5 inches for the outlet. 
Tanks for circulating the water are generally made 



A TALK ABOUT ENGINES 131 

with a capacity for furnishing 20 to 30 gallons per 
indicated horse-power. This rule may be taken 
as about correct, but, if anything, it is rather an 
over-estimation of quantity necessary." 

All the foregoing was made as clear as possible 
to the listeners by Mr. Gregg before the children 
went to bed. 

Next morning Fred called up his artist friend, and 
got him to come down to gild the name ''Caroline" 
on the boat before the next coat of varnish should 
be applied. The artist made an outline of the 
name while George and Jessie stood by and watched 
the process with considerable interest. They saw 
him measure oflf each letter, outline it with a 
pencil lightly, and then paint inside the lines with a 
substance known as ''gold size," obtained from any 
store dealing in painters' supplies. While the size 
was still sticky the artist applied "gold leaf," which 
he had brought in a little book along with him. Jessie 
was surprised to see him cut the gold with a thin 
pallette knife, having a blunt but smooth edge. 
She watched him pick up the small pieces of gold 
with a camel's hair brush, which he rubbed in his 
own hair now and again whenever it would not pick 
up the gold. The metal was applied bit by bit over 
and beyond the lines of the letters, and a light puff 



132 MECHANICS 

of breath forced it down to the size. When one side 
of the boat was finished, so far as laying on the coat 
of gold was concerned, Jessie was very much dis- 
appointed, as the name seemed merely a smudge. 
She could not make out the letters, but the artist 
told her to wait until to-morrow and he would show 
her how well they could be seen. Next day with 
a flat camel's hair brush he dusted away the surplus 
gold, and the letters showed up in good style, much 
to the gratification of Jessie and George. This 
part of the work being done, the boys took down 
their varnish pots, and gave the little craft another 
coat, to make her quite spruce and gay. 

Fred, and Nick, who was still in the employ 
of Mr. Gregg, laid off a space on the ground for 
tables and seats to accommodate the young folks 
who were coming to the launch on the following 
Wednesday. Nick found a number of old cedar 
posts, and with a saw cut off 18 pieces about two feet 
long and as many more twice that length. The 
first were intended to place the seats on; the second 
lot were to sustain the tables. The spots for the 
tables were chosen, measured off, and small stakes 
driven into the ground to show where the posts 
were to be placed. Five posts were intended for each 
table — two at each end, two feet apart, and nine 



A TALK ABOUT ENGINES 133 

feet apart in the length of the table. The single 
post was placed in the centre of the table both ways. 
When the stakes were all in place, Nick made holes 
deep enough to take in the posts so that their tops 
measured just two feet and two inches above the 
level of the ground. The tables were to be two feet 
and six inches high when finished, as that is the 
regulation height. It was attained, in this case, as 
follows — First by the height of the posts from the 
ground, two feet two inches; then by a plank two 
inches thick laid across the two posts, making the 
height two feet four inches, and the table top, 
two inches thick, laid on these cross planks, which 
brought it up to the required height. A piece of 
plank the same thickness was nailed on the centre 
post across, so that it would support the table top. 
Planks that had been used in the loft of the old barn 
did service for the table tops, bearing pieces, and 
the bench seats. The last were constructed in the 
same manner as the tables, the short posts being let 
into the ground — three under each seat — and 
fourteen inches above ground so that when the 
plank seat was nailed on top of them, the seats were 
just sixteen inches, the regulation height of stools, 
benches, and chairs, though it is sometimes varied 
to suit conditions. The benches were placed about 



134 MECHANICS 

four inches out from the edge of the table and were 
found to be ''just the thing." 

When Nick had planted the first post for the 
tables and got it the right height, he took that one 
for his guide and by the aid of a long parallel 
straight edge which he laid on the guide post and 
the one he was setting, and also a spirit-level on the 
straight edge, he managed to get all the posts alike 
in height and this made the tops of the three tables 
nice and level. It was quite an achievement to 
have three large tables and six long seats placed in 
"picnic style" at so small a cost and with so little 
effort. 

In order to have the tables and seats neat and 
clean, George turned on the garden hose and gave 
them a good wash off, and when they were dry again 
the place was as inviting as a country hotel dining- 
room. When Mrs. Gregg, Jessie, and Grace Scott 
had the tables set and garnished for the launch, 
the lay out was charming, none the less so because 
it was a little rustic. 

Another coat of varnish, the third, was given 
the boat the day before she was to be launched, 
and Fred had a strong rope attached to the winch, 
with a heavy iron hook fastened to the end of it. 
A stout iron ring was bolted to the stern of the 



A TALK ABOUT ENGINES 135 

boat and made secure. Mr. Gregg had purchased 
a number of small flags and "burgees" and had one 
made with the name '^Caroline" in large letters 
wrought on it, ready to be unfurled when the 
launch was made, and Walter Scott, his mother and 
sister Grace, and others had been invited to attend. 
A number of temporary swings were fixed up by 
Nick and Fred to the trees, some for the large folks, 
others for the smaller ones, and everything was at 
last ready for the great event, which was to take 
place the next day at two o'clock. 



VI 

PROPELLER AND OTHER SCREWS 

WEDNESDAY morning was light and 
sunny and the boys were up and dressed 
somewhat earlier than usual, so, while 
waiting for breakfast, they took a stroll down to the 
river, where they found their father looking over the 
grounds and examining tables, benches, swings, 
and particularly the foot-bridge; for, as he told 
Fred, "it was very likely all the guests might be 
on the bridge at one time and the combined weight 
would be rather trying if it had not been securely 
put together." He satisfied himself, however, that 
the bridge was strong enough to support three 
times the weight it would be called upon to sustain. 
Everything else seemed to be sufficiently strong, 
to apprehend little danger, no matter how much the 
children romped. 

Nick had the grounds nicely raked off; the decayed 
branches and shrubs he moved, and made everything 
about the place as clean and as neat as possible. 
Flags and other decorations were hung or placed 

136 



PROPELLER AND OTHER SCREWS 137 

about the grounds, on the trees and buildings, but 
particularly about the tables and the boat house. 
Newspapers were spread over the tables, linen 
covers above them, and the whole surroundings 
took on a most festive appearance. 

It was just 11 o'clock when The Mocking-Bird 
arrived and tied up to the new dock. On board 
were Mrs. Scott, Grace, and the maid, who came to 
help, besides several of the invited guests whom 
Walter had brought down with him. All were 
welcomed by Fred, Jessie, and George and then 
the women visitors went to the house to assist Mrs. 
Gregg. 

Mr. Gregg came home from his office earlier than 
usual and took a half holiday in honour of the 
occasion. The guests, in little groups, arrived on 
time, and before the clock struck two Nick had 
everything prepared for the launch. He and Fred 
and George had the Caroline nicely placed on 
the skid, ready to "let go" the winch, and a flag 
pole was fixed up on the bow of the boat. To this 
the flag with the name on it was lightly tied, in such 
a manner that when a string was pulled it would 
unfurl, and show the name. The string looping 
up the flag was left long enough to enable Mr. Gregg, 
standing on the dock, to hold the end in his hand, 



138 MECHANICS 

and by pulling it to loosen the flag as soon as the 
boat touched the water. 

Everything being ready, Walter Scott invited 
as many of the young people to get into the Mock- 
ing-Bird as could crowd on board with comfort, 
and each was provided with a whistle or a horn, 
as he ran his boat half way across the river. The 
children on shore were also given horns and whistles, 
and all were told to blow as loud as they pleased 
when the boat touched the water. Mr. Gregg, 
having Mrs. Gregg and Mrs. Scott standing beside 
him, gave the word, "Ready!" Nick and Fred 
answered, ''Aye, aye, sir!" and the master of cere- 
monies called out in a loud voice: ''Let her go!" 

Nick freed the winch, Fred and George gave a 
little push, and the Caroline slid down the skids, 
into the water, without the least hitch. The horns 
and whistles made a great din, and when the flag 
was let free to open up and show the name "Caro- 
line" there was another blast of noise by horns and 
whistles, mingled with voices of the younger people, 
who cried out with all their might, " Hurrah for the 
Caroline!'' 

The launch being over, and everything having 
gone all right, the young people were called to 
lunch. They all sat at the tables which were nicely 



PROPELLER AND OTHER SCREWS ISD 

garnished and well supplied, and there was plenty of 
small talk, and much laughter and jollity. After 
lunch, Fred, Walter and George boarded the Caro- 
line supplied her with gasolene, and tried to run her. 
They found a little difficulty in starting, but after 
the engine was warmed up a little, she went olBf 
beautifully, and answered her tiller in fine style. 
The boys ran her up and down the river for a while, 
then tied her to the dock, and Walter and Fred in- 
vited all the girls to "Come and have a sail." The 
boys were promised one when the two boats returned, 
which they did in the course of half an hour. The 
swings were put in use, dancing and romping began, 
and the afternoon was passed in fun and frolic. 

In the evening, Mr. Gregg, Jessie, and the boys 
took a trip, and Mr. Gregg was well pleased with 
the boat's performance, particularly with the work- 
ing of the screw. In mentioning this, he awakened 
the curiosity of George, who reminded his father 
that he had not yet explained to them about the 
screw as a mechanical power. 

That evening George was told to bring his black- 
board and equipment into the den, and the father at 
once began explaining the mechanical qualities of the 
screw. He told of its great usefulness in the indus- 
trial arts. As one of the mechanical powers. 



140 MECHANICS 

it may be considered an inclined plane, wrapped 
spirally round a solid cylinder. The advantage 
gained by it depends on the slowness of its forward 
or backward progress, that is, on the number of 
turns or threads, as they are called, in a given 
distance. It is always used in combination with a 
lever of some sort. When employed as a lifting 
machine it has great power, and is used to produce 

compression or to raise or 
move heavy weights. If a 
screw is formed on the inside 
surface of a hollow cylinder, 
it is called a nut, and used 
to overcome a resistance; 
either the screw or the nut 
may be fixed and the other 
movable. The acting force is 
generally applied at the end 
of a lever or wrench or rim 

Fig. 33. Theory of screw ^f ^ ^j^^^^j pjg 33 j,^^j.^_ 

sents a screw and nut operated by a lever 
or length of radius r; p is the pitch of the screw 
or height of the inclined plane for one revolu- 
tion of the screw. W is the resistance at the 
nut and P is the force at the end of the lever 
r. Remembering that, while the resistance W 




PROPELLER AND OTHER SCREWS 141 

is raised the distance p the force P revolves 
around a complete circle and moves a distance 
^irv . Let us now apply the condition 2 work— 



and we have V^irv — Wp = or 



p2 'rrv [6. 



The worm gear (Fig. 34) is a special case of screw 
and nut, where the 
latter is replaced by 
a toothed wheel 
called a worm wheel. 
The teeth work in 
with the thread of 
the screw or worm, 
and thus, as the worm 
revolves, the worm 
wheel revolves about 
its axis. P is the 
force acting on the 
worm at a radius r, 
t' is the pitch radius 
of the teeth in the 




W 

Worm wheel and screw 



Fig. 34. 

worm wheel and r" is the radius of the drum on 
which W acts. Let K, corresponding to W in 
equation W P [6], be the force at the pitch circle and 

worm threads due to the force P; then K= LJ 



142 MECHANICS 

Now apply 2m = to the worm wheel and we 
have Kr" = Wr" or K = wr'' (8). Substituting the 
value of K in (7) in equation (8) we have P27n/= 
Wr" or P27n/=:Wr"p [9]. Now it is evident that 
the distance ;p' moved by W while K moves through 
the distance p is to p as r" is to r^ ot p' : p :: r" : r' 

Qr Jp —^ (10). Substituting this value of -^-7— in 
r T 

equation (9) we have V^irv = W p' or the condition 

2 work = 0, since %7rv is the distance moved by 

(P) while W moves the distance p\ 

No provision for friction has been made in any 
of the examples given, so that allowance must be 
made for this propensity whenever any of the fore- 
going rules are applied to practice. The amount 
of allowance required will vary and must be made 
to suit conditions. 

An endless screw is sometimes used as a component 
part of graduating machines, counting machines, 
etc. It is also employed in conjunction with a wheel 
and axle to raise heavy weights. The distance 
between the threads of the screw is called the 
pitch or step. These threads are sometimes square, 
sometimes acutely pointed or edged, sometimes 
rounded off on the edges. Power is often applied 
by means of a lever or other contrivance attached 



PROPELLER AND OTHER SCREWS 148 

to the end of the screw, or by a long handled wrench 
(a monkey wrench for instance), which, when turned, 
moves forward in the direction of its axis, over- 
coming resistance. In the case of the screw-jack, 
it may be used to raise a heavy weight. The rela- 
tion between the force applied and the resistance to 
be overcome is important to note, for every time 
the screw performs one revolution it moves forward 
through a distance equal to the space between one 
thread and the next. 

The Archimedian screw 
we have read and heard so 
much about is simply a hollow 
pipe wound around a cylinder. 
It was often used in olden 
times for raising water, but is 
now only occasionally applied. 
The lower end of the spiral 
pipe is, of course, left open and 
immersed in water, as shown 
in the illustration (Fig. 35), 
a device for raising water, the 
being the motive power. The 
of the wheel has extending through it a spiral 
passage, the lower end of which is immersed in water; 
and the stream, acting upon the wheel at its lower 
end, produces its revolution, by which the water 




Fig. 85. Archime- 
dian screw 

supply stream 
oblique shaft 



144 MECHANICS 

is conveyed upward continuously through the 
spiral passage and discharged at the top. An 
arrangement like this could easily be constructed 
at the edge of most rivers to raise water to irrigate 
the grounds, if so desired, and the little flutter 
wheel at the bottom of the inclined shaft would be 
powerful enough to lift all the water required. Fred 
thought that would be a great scheme, and deter- 
mined to try his hand at it one of these days, but 
he was told that a wheel of that kind could only 
work at intervals, as the river's flow was often 
running in opposite directions owing to the inflow 
of the tidal water. 

These Archimedian water raisers are often fitted 
with a crank handle on top, and a man, standing on 
a platform, turns the crank and thus 
lifts up all the water the machine 
will carry. The Archimedian screw 
is used for many other purposes than 
raising water. With wide, thin wings, 
Fig. 36. Spiral similar to the construction shown 

conveyor , . 

at rig. 36, and enclosed m a case 
or jacket, it is employed by millers to convey 
grain and other mill requirements, and it is also good 
for moving coal, ore, gravel, and like material, but 
when used for these coarser purposes the propelling 




PROPELLER AND OTHER SCREWS 145 

blades are made of steel, riveted or bolted to a 
strong iron shaft. The case or jacket containing 
the revolving blades, if horizontal, need not be 
covered on top, as the blades will propel the material 
without jamming or clogging, if the jacket is smooth 
inside, and fits fairly close to the blades. 

This style of a 
screw may be used 
as a sort of tur- 
bine water wheel, 
if cased in a cylin- 
drical penstock or 
tube, and a body 
of water allowed to ^'^- ^^' "^^^^^^ ^^ ^^''^^ ^^^ g^^^ 

fall into the upper end of the tube. The force of the 
water will give a rotary motion to the blades and 
shaft, and, the latter having a geared wheel or pulley 
attached to its top, motion is imparted to other 
shafts and wheels. 

Another application of the screw is shown at 
Fig. 37, where one is arranged on a shaft or axle 
to give a rotary motion. This device is called a 
"worm and wheel," and is frequently used in the 
make-up of machine engines and mathematical 
instruments. The illustration shows how the power 
or force of a screw may be conceived. For instance, 




146 MECHANICS 

suppose the wheel C has a screw on its axis working 
in the teeth of the wheel D, having 48 teeth. It 
is plain that for every time the wheel C and screw 
are turned round by the handle or crank A, the 
wheel D will be turned once round. Then, as the 
circumference of a circle, described by the crank A, 
is equal to the circumference of a groove round the 
wheel D, the velocity of the crank will be 48 times 
as great as the velocity of any given point in the 
groove. Consequently, if a line C goes round the 
groove, and has a weight of 48 pounds hung to it, 
a power equal to one pound at the handle will 
balance and support the weight. To prove this by 
experiment, let the circumference on the grooves 
of the wheels C and D be equal to one another; 
and then if a weight H, of one pound, is suspended 
by a line going round the groove of the wheel C, 
it will balance a weight of 48 pounds hanging by 
the line G; and a small addition to the weight H 
will cause it to descend, and to raise the other weight. 
If a line C, instead of going round the groove of 
the wheel D, goes round its axle I, the power of the 
machine will be as much increased as the circumfer- 
ence of the groove exceeds the circumference of the 
axle, supposing which to be six times 8, then one 
pound at H will balance 288 pounds, hung to the 



PROPELLER AND OTHER SCREWS 147 

line on the axle; thus showing the advantage of 
this machine as being 288 to 1. A man who can 
hft by his natural strength alone, 100 pounds, by 
making use of this combination, will be able to raise 
28,800 pounds alone, and if a system of pulleys 
were applied to the cord H, the power would be 
further increased to an amazing degree. 

When a screw and wheel are attached, as shown, 
the screw is sometimes called a **worm" and some- 
times an "endless screw." 

The propeller wheel (Fig. 38) is a screw having 
a large helical dimension. The example shown has 
four blades, each of which, when rotated, may be 
said to make one quarter of a revolution and when 
at work in the water has the same effect 
as the working of a nut, producing 
motion in direction of the axis and 
so propelling the boat or vessel. The 
action of the wheel pressing back- 
ward against the water tends to push 
the craft forward. 

rnu- £ 1 n . , ^'«- ^^' Complete 

inis ngure snows a propeller with screw propeUer 
four blades, but two and three bladed ones, 
particularly for small craft, are mostly used. 
The Caroline carries a two bladed screwf and 
her performances will be entirely satisfactory. 




148 MECHANICS 

The blades, of course, are exactly in line with 
each other on the shaft, and equally balanced, 
or of equal weight. A three-bladed propeller 
should have its extreme points in a horizontal 
plane, so that they will form an equilateral tri- 
angle. 

The principal features of a propeller may be 
described as: diameter, pitch, area, speed of rev- 
olution, and slip. The diameter is that of the 
circle described by the tips of the blades. The 
pitch, considering the propeller to be a portion of 
a screw, is the amount which it advances in one 
turn, supposing it to travel in a solid medium. 
The blade area is the actual area of all the 
blades. 

The speed of the revolution is customarily reck- 
oned in turns per minute. The slip is the difference 
between the amount which the propeller actually 
advances per turn and the amount which it would 
advance if turning in a solid medium. For example, 
if the pitch of a screw is 30 in. it would advance 
30 in. at each turn if there were no slip. Suppose 
that it only advances 20 in. per turn, then the slip 
is 10 in. per turn, or as usually figured, 33J^ per 
cent. As a further example, suppose a propeller 
of 30 in. pitch, turning 300 turns per minute, drives 



PROPELLER AND OTHER SCREWS 149 

a boat at the rate of 6 miles per hour. The advance 

30 
of the propeller in feet per minute is -j^ X 300=750 

while the advance of the boat is — ^ — = 528 ft. 

per minute. The slip is then 750 — 528 = 222, or 

222 
as a percentage, r^ =29.6 per cent. It might 

seem at first sight, that a perfect screw propeller 
should have no slip; but this is a practical and 
theoretical impossibility. 

The most important dimension, from the stand- 
point of the absorption of power, is the blade area. 
A certain blade area may be obtained by a rela- 
tively wide blade on a small diameter, or by a narrow 
blade on a relatively large diameter. In the former 
case the area of the blades bears a greater propor- 
tion to the area of the circle through the tips than 
in the latter case. There are certain limits for this 
proportion of [blade to disc area for well-designed 
wheels, beyond which it is not well to go. These 
are as follows: 

For two blades .20 to .25. 

For three blades .30 to .40. 

For four blades .35 to .45. 

This means that for a 24 in. diameter propeller, 
whose disc area is 452 sq. in. the blade area should 



150 MECHANICS 

not, for ordinary use, be made greater than these 
proportions, as the blades then become so wide as 
to interfere one with another. Of course where a 
propeller, for shallow draft, must be unusually small 
in diameter, the proportion of blade area can be in- 
creased, but with some loss in economy. Strictly 
speaking, for a well balanced propeller, the blade 
area fixes the amount of power which the propeller 
can deliver, while the pitch, combined with the turns 
per minute, governs the speed. As a matter of 
fact, for the average propeller the two are closely 
related, each having a certain influence upon the 
other. To illustrate, a propeller may have a small 
blade area and so great a pitch that the blades act 
somewhat like fans and simply churn the water, 
ofiFering great resistance and absorbing the power 
of the engine, but doing Httle effective work toward 
driving the boat. 

To get the measurements for a wheel required 
to perform a given service, say a three-bladed 
propeller for a small boat or tug of 20 nominal or 
75 indicated horse-power: — assume that the size 
determined on is 4 ft. 6 in. in diameter and 7 ft. 
6 in. pitch, the diameter of loss may be assumed 
to be 8 in. swelled to be 11 in. in the middle, and 
11 in. long. The tug would be, say, 60 ft. long, 



PROPELLER AND OTHER SCREWS 151 

12 ft. beam, and 7 ft. deep. First delineate the 
path of the point and root of one blade through 
half a revolution as in Fig. 39. This should be 
drawn to a scale of not less than 13^2 in. to 1 ft. 
by the ordinary method of projecting a screw 
thread. The semicircle shows the half plan with 
twelve equal divisions, and the half elevation is 
divided into the same num- 
ber of equal parts. The 
helix or thread is then ob- 
tained by drawing the curves 
through the intersections of 
similar divisions. Then a 
h will be the helix for point 
of the blade, and c d the 
helix for the root of the 
blade. These will be found 
to be practically straight lines 
which might have been obtained in a simpler man- 
ner if intended for a working drawing only; but it 
is useful to have demonstrated the proper nature 
of the full curve. 

The practical way of setting oiBE the blade follows : 
First for dimensions: as 20-in. (pitch) is to 11 in. 
(length of boss and therefore virtual length of 
propeller), so is 169.6 in. (circumference due to 



■^ 




i II 








ll 


7 






1 


z 






jf\ 


7' 


«* 

• 




!:^ 




- 'v^ 


-■>'«*: 


- • 


- - ■> 


z 








2 ' 








f T ' 


' i 


i- 




\ 


1 
1 

k. 1 


y 



Fig. 39. Diagram screw lines 



152 

outer diameter) 



MECHANICS 
to the length 



of circumference 



occupied by the blade, ^^^_^^^^ =20. 73, say 20^ in. 

y 

In Fig. 40 describe a circle equal to the diameter 
of the propeller, and on each side of the centre line 
step off 20% in. to half the scale, making the whole 
length of arc to scale 20% in. Draw vertical hues 
from the ends of the arc, and from the arc on the 

centre line set up a height 
of 11 in. and draw hori- 
zontal lines. Join a 6, and 
this will be the angle of 
the end of the blade. On 
the elevation of the pro- 
peller circle describe a 
small circle equal in dia- 
meter to the faces of the 
boss; draw radical lines 
from the ends of the arc first found, and from the 
intersection with the boss circle draw vertical lines to 
cut the horizontal lines of the plan of boss. Join c d, 
and this will be the angle of the blade at the root. 
Now describe an arc at every three inches from the 
circumference within the radical lines; or for large 
propellers every 6 in. Draw vertical lines from the 
intersections of the arcs with the radical lines to 




Fig. 40. Part of screw blade 



PROPELLER AND OTHER SCREWS 153 

meet ac and bd, as shown, and joining the points 
thus found, the diagonal Hues will represent the 
plan or angle of the blade to each 3 in. diflference 
of radius — in other words, its real width at the 
different points, supposing it to be a plain geometri- 
cal portion of a screw thread. As a matter of fact, 
the blades are always more complex than this, the 
edge being curved to enter the water more easily, 
to avoid vibration, and also to lessen the risk of 
fracture in the event of striking any object in the 
water. Sometimes the blades are curved in the 
opposite direction, as if the 
points were being left behind 
while the blade is advancing. 
The next step is to draw a 
flattened elevation or devel- 
opment of one of the blades, 
in order to give the actual 
curves of its outline, and after- cmcsu&is «. 

ward its thickness at various 
points. Draw a horizontal line ^^s- ^^' ^^^^ of screw blade 
from c and / (Fig. 41), and through this a centre line. 
This will give the length of the bladefrom the boss, and 
the centre line of the propeller shaft may be added be- 
low. Then take the lengths ab and cci from Fig. 40, and 
set them off on Fig. 43, as shown, joining all fourpoints. 




154 MECHANICS 

This figure would be the true outline of the blade if 
there were no curves. The actual outline is found 
by drawing the curves according to the dimensions. 




Fig. 42. Propeller lines complete 

Lay out the propeller, as shown m Fig. 42, which 
will give the elevation of the blades, all being alike, 
j^ To find the area of a propeller blade, mark it off 
in parallel lines, say 3 in. apart, and^note the width 




PROPELLER AND OTHER SCREWS 155 

at the centre of each portion. Add the widths to- 
gether, and divide by the number of widths. This 
will give the mean width, which must then be mul- 
tiplied by the length of blade to obtain the area. 
If the measurements are all in inches, the result 
should be divided by 144 to give the area in square 
feet, and then be multiplied by the number of 
blades to give the total 
area. 

To measure the pitch of 
a propeller, lay it down on 
a level surface, hold a 

, . 1 , 1 , 1 Fig. 43. Angle of propeller blade 

straight edge level across 

centre of blade with a square up from the lower 
edge, as in Fig. 43. Measure the distance B and H 
and the radius R from the centre to the part where 
the measurement is taken; then B : 2wR ::H to 

^wIMT 

pitch, P or P= g — The measurements may be 

made in more than one place and the average taken, 
as the blades are sometimes twisted slightly. 

Scaling only from the drawing, P= ^ 

2x3.1416x1.6x1 r. f. ^ ' 

Y^ =7.74, say 7 ft. 9 m. pitch, 

whereas the intended pitch was 7 ft. 6 in. 



156 MECHANICS . 

A good illustration of the use of the screw may 
be seen in the carpenter's auger, used for making 
or boring holes in wood. These tools are provided 
with a small tapered screw on their points, and this 
is followed by cutting edges and a larger spiral. 
The larger spiral is for the purpose of drawing up 
the chips or shavings. Another tool is made having 
two blades attached to the bottom of an iron bar 
formed like the blades of a propeller, which is some- 
times employed for boring or digging post holes in 
clayey or soft soil. The machine is turned by a 
cross handle on top, and is frequently drawn up to 
bring out the soil until the hole is deep enough. 
The ordinary wood screw is one of the most useful 
of contrivances for fastening wood together, and for 
attaching to surfaces, hardware, ornaments, or other 
materials. The adhesive strength of nails is already 
shown, and the adhesive strength of wood screws, 
according to Bevan, is set down as follows: 



WOOD SCREWS 

The following are the thicknesses or diameters corresponding to the list 
numbers. Other thicknesses can be interpolated, each size varying in suc- 
cession ^in, — t 



No. 


'loo 





1 


5 


10 


14 


18 


22' 


27 


32 


40 


Thicknesses in 
parts of inches 


h 


1^ 


^ 


i 


^ 


¥ 


A 


f 


^ 


i 


1 



PROPELLER AND OTHER SCREWS 157 

An ordinary 2-m. wood screw, driven through a 
3/^-in. board into hard wood, was found to " be 
790 lbs., and a force of about 395 lbs. was required 
to extract it from soft wood. 

When screws are hard to drive or screw in place, 
a long screw-driver should be used, as screw-drivers 
with long handles seem to have a much greater 
leverage than short handled ones in driving screws 
home. Screws, however, are often split at the head, 
if care is not taken when using a long driver. 

If a screw is rusted, hard to move or withdraw, 
it can be loosened by applying a hot iron to the head 
and making it hot. The heat expands the screw and, 
of course, makes the hole larger, and when the screw 
cools it contracts a trifle so that it may be with- 
drawn quite easily. 



VII 

AEROPLANES 

GEORGE and Fred were so much interested 
- in the Caroline that they neglected to 
do some work Mr. Gregg had suggested, 
but a hint or two from him reminded them that 
saihng the new boat every day would get so monoto- 
nous it would cease to be a pleasure. Fred, there- 
fore, set to work to put the new property in apple- 
pie order, by cleaning up the grounds, burning the 
rubbish, and tidying the place generally. Nick, 
not being needed longer, was allowed to go, with 
the promise that whenever a man was required 
about the place, he would be chosen. His de- 
parture left all the work to Fred and George, both 
of whom gladly accepted the duty. 

The first thing was to set up three or four long 
benches on the river bank. These were built 
exactly in the same manner as the seats alongside 
the tables. Three short posts were let into the 
ground for each seat, and a good, sound plank 
spiked solid to their tops. One of the seats was 

158 



AEROPLANES 159 

made four or five inches lower than those at the 
tables, so as to accommodate the smaller children. 
The two boys did the work well, though they found 
it a little hard to dig the holes in the ground and 
saw off the posts. George's hands became a 
little blistered and sore, but his mother soon cured 
them, though she warned him against working 
too hard or too long at a kind of labour to which 
he was not accustomed. 

After tea was over, it being a fine, warm, spring 
evening, the whole family went down to the river's 
edge to sit on the new seats and enjoy the view. 
Noticing the current of the river, Jessie questioned 
her father about its going one way sometimes, and 
then turning in the other direction. Her father 
explained that it was the movement of the tide 
that made the water flow against the stream at 
times, and that when there was no tide, the current 
took its natural course. This explanation did not 
seem to satisfy Jessie, and she asked why there were 
any tides. So Mr. Gregg promised to explain 
all that was known about tides to her in the near 
future. "I wish you would," said George, "and tell 
us about kites, balloons, and flying machines." 

*'0h, yes," said the father, ''I'll try to do that 
to-morrow night." 



160 MECHANICS 

*'I'm glad, father/' said Fred, "as I want to try 
and make a model for George before the Fourth 
if I can, so he can have one to fly across the river 
that day, instead of fooHng with fire-crackers and 
other dangerous fireworks." 

'^That's a good idea, Fred," said the father, 
"A model aeroplane, decorated with silk flags 
would give a great deal more real pleasure than 
firing off all the fire crackers in the state. It would 
be quite easy, now you have a boat, for one of 
you to be on this side of the river, the other 
on the opposite side, and to keep a number 
of little machines going to and fro across the 
water." 

George seemed deKghted at the prospect. Walter 
Scott had also been stricken with the aeroplane 
fever, and was busy making models, though, as yet, 
he had not finished any. Both Fred and George 
were anxious to hear all their father had to say 
concerning these machines, as they knew he would 
be thorough, and make it all plain. Mr. Gregg 
told the boys that to explain fully the theory and 
practice of building an aeroplane of any kind would 
take some time, but he would willingly give it for 
their benefit, and would discuss the subject of 
aeronautics at length so as to give them some pointers 



1 


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Copyright, 191 1. by Under\vood & Unuernood, N. Y. 

The Monoplane Model Complete 
'A Model Aeroplane, Decorated with Silk Flags Would Give a Great Deal 
More Pleasure Than Firing off AH the Fire Crackers in the State" 



AEROPLANES 161 

about the design and practical making of flying 
machines. 

On the following evening, Jessie did not forget 
to remind her father of his promise to tell them all 
about "air-ships and things," as she put it. 

"All right, my dear," said Mr. Gregg, "I'll take 
you all into the 'lion's den' shortly after tea. 
But tell me, why is it you are so anxious to know 
all about * air ships and things'?" 

"Oh! that's all right, papa; Fred is going to 
build a great big ship, as soon as he knows how, 
and he has promised to take me up to the clouds 
in it for a ride." 

"Well, my dear, it will take some time to tell 
you all about these things but I will make an at- 
tempt. For ages man has wanted to fly, and the 
Greeks tell us of a mythical personage named 
Icarius, and another named Daedalus, who flew 
to the sun. There have been many attempts to 
fly, both with and without mechanical aid, but 
history gives us nothing definite on the subject 
until about the year 1785, when two Frenchmen, 
named Montgolfiers, built a balloon sixty feet high 
and forty-three feet in diameter, and filled it with 
heated air. Attached to the bottom was a light 
cage made of wicker-work, into which were placed 



162 MECHANICS 

a lamb, a duck, and a rooster. The balloon was cut 
from its moorings and rose to a height of over 
1,400 feet so that these animals were the first that 
ever went up in a machine made by hands. 

*'The Montgolfiers attained considerable noto- 
riety, and out of their experiments grew the pres- 
ent dirigible Zeppelin, which measures 446 feet in 
length, over 42 feet in diameter, and is capable 
of carrying eight able-bodied men a distance of 
over 900 miles. This great machine is charged 
with gas, and driven by four three-bladed propel- 
lers, which are run by two gas engines of 110 horse- 
power. This is simply a monster balloon, suspended 
in the air by 529 to 700 cubic feet of hydrogen, or 
coal gas, which is much lighter than ordinary air. 

*'It may be said there are four distinct kinds of 
flying machines, each unlike the other in construc- 
tion and in principle. The first is the old-fashioned 
balloon which has an envelope or covering of some 
air-tight fabric, and is inflated with a light gas. To 
it is attached a framework of some kind called a 
Nacelle, that carries the aviator, the steering gear, 
and the necessary engines to operate the propeller 
or propellers. 

"The second kind of flier is the aeroplane, which, 
as its name indicates, is supplied with 'air planes,' 



AEROPLANES 163 

that give it the power of rising and falling at the 
will of the operator when the machine is in motion. 
These planes play a very important part in the 
successful operation of the machine, as I will ex- 
plain later. The first type of machine is classed 
as a 'lighter-than-air' machine or a balloon, while 
the planes of all kinds are classed as 'heavier-than- 
air' machines. Among other types of * fliers,' 
there is the helicoptere, which is raised by screws 
or propellers on vertical shafts. These revolve 
rapidly, and drive the machine upward, just as 
the propeller on the Caroline drives her forward 
when in rapid motion. Another type, nearly aban- 
doned, is called the ornithoptere, or *wing flyer.' 
These machines are built to operate like the wings 
of a bird, and are provided with the necessary 
contrivances to work the wings, both vertically 
and horizontally. This type, like the helicoptere, 
is not considered practicable, and is virtually 
abandoned, so that the field is now left altogether to 
the 'lighter-than-air,' and the aeroplane machines. 
I do not intend giving you any instruction regarding 
balloons, or dirigibles, as I think such is unnecessary, 
but will confine myself altogether to the discussion 
of aeroplanes. 
^"''It must not be supposed because of the name 



164 MECHANICS 

aeroplane, that the so-called plane is a real plane; 
it is not. The front edge of an airship plane must 
always be curved, as shown in Fig. 44, so that 
the air strikes the under surface and is forced under 
the plane, to buoy up the machine as it moves for- 
ward; or, to put it another way, there must be a 
current of air either natural or artifical on which 
the machine must float, or it will be drawn by gravi- 
tation to the earth. While we cannot see air or 
wind, we know from experience that it has great 
power, and for thousands of years ships have been 
propelled across the seas by this force, acting on 
sails of some kind. We know how difficult it is 
to travel against a high wind, and it is this quality 
in the air that makes it possible to travel through 
it. The resistance of the atmosphere makes it 



tmpmgin^ ^f 






Fig. 44. Aero-curves 

possible for the aviator to hold his machine sus- 
pended in opposition to the laws of gravity, and 
to drive it forward and upward by means of the 



AEROPLANES 165 

revolving propeller acting against this resistance, 
the motor acting on the same principle and manner 
as the wheel or propeller of a boat when it is urged 
forward. If, as I have seen George do, we take 
a flat stone, a piece of slate, or flat metal, and throw 
it along the face of the river, in such a manner that 
its flat surface strikes the surface of the water, it 
will skim along, striking the water at intervals in its 
course, until the force given by the hand that 
threw it is exhausted, when it will drop and sink. 
The water, though lighter in equal bulk than the 
stone, is aided by the force given by the hand 
to buoy up the stone until the force is expended. 
The curve on the front edge of the planes, when the 
machine is in motion, really takes in more air than 
the space allowed for it under normal conditions, 
and it may be said to be compressed to some extent. 
If the wind be blowing in the 'teeth' of the ma- 
chine, the resistance of the air will be greater, and 
the buoyancy of the machine increased. So, also, 
if the machine is travelling rapidly, the motion will 
increase the resistance and the buoyancy at the same 
time. The moment the propellers stop, gravitation 
grasps the machine, and if the planes are kept 
evenly balanced it will quietly and gently descend 
to the earth. You must particularly bear in mind 



166 MECHANICS 

that wind blowing in the face of a machine tends 
to hold it up, and that a machine flying rapidly 
makes its own wind, so that the results are the same. 

''The curve on the front of the planes may be 
called an 'aero-curve,' and much of the success 
of the machine depends on this curvature of the 
planes, which gives to the inside of the plane a 
concave shape of a peculiar character, and to the 
outside a convex form. 

"If you examine the rough drawing I made for 
you on the blackboard (Fig. 44) you will notice 
that the upper or convex curve is different from 
the under or concave one, and it is upon this differ- 
ence in curvatures that many of the flying qualities 
of the machine depend. This little section showing 
the different curves is the one used by many of 
the successful aviators, though some prefer the 
form invented by Sir Hiram Maxim, shown in 
Fig. 44a, which does not differ very materially from 

the previous section 
^^^^ ^^^^s*»s*i«s,,^^^^ shown. In all cases, 
':^--'*" however, the accept- 

Fig. 44a. Maxim's aero-curve ^^ plane is OUC of a 

curved vertical sec- 
tion in which the convex side is uppermost and the 
upper surface more curved than the lower. Al- 



AEROPLANES 167 

though different authorities disagree as to why 
this shape of plane is best, all agree that it is so. 
Sir Hiram Maxim's theory is that the air follows 
both the upper and lower surfaces of the plane, as 
shown in Fig. 44a, while Phillips holds that the air 
follows the lower surface of the plane, and, striking 
the hump, shown at A, Fig. 44, is reflected off the 
upper surface of the plane, thus forming a partial 
vacuum on the upper surface, which gives an ad- 
ditional upward pull to the plane. There is, 
however, little doubt that most of the work is done 
by the force exerted on the lower surface of the 
plane. 

''Another consideration that enters into the de- 
sign of the plane is the aspect ratio, or the ratio 
between the depth of the plane fore and aft, and the 
width or span. Authorities do not agree about 
this latter consideration. A practical aspect ratio, 
one states, is 6 to 1, as, for instance, a plane 39 
feet spread by 6 feet 6 inches in depth. In Santos 
Dumont's Demoiselle the aspect ratio is only 3 
to 1. The ideal plane, however, would be a plane of 
great length and little depth, but this is impossible 
in the practical machine, as a plane of excessive 
length would greatly weaken the construction of 
the machine. Again, the different authorities do 



168 MECHANICS 

not agree as to the shape of the ends of the planes. 
Lanchester says that an efficient plane must be of 
rectangular form, and the Voisin and Curtiss planes 
are rectangular, whereas the wings of the Bleriot 
and the Wright planes are decidedly curved at the 
tips. 

'*I will show in other illustrations the method 
of placing the planes on such machines, as made 
by Curtiss and some other noted aviators. 

*'I think I have said sufficient to give you a fair 
idea of the reason why an aeroplane can be made 
to navigate the air, but I have not told you how 
its direction can be controlled. No doubt, if the 
air were always still and not subject to change, 
there would be but little difficulty in controlling 
the direction of the machine, but, unfortunately, 
this is not the case, so provision has to be made 
to meet various changes as they occur. A down- 
ward current of air causes the plane to change its 
inclination to the horizontal, so that it will not 
support the weight, and the machine falls to the 
ground. To overcome this unsatisfactory state 
of things, small auxiliary planes are used to coun- 
teract the eflfect of varying air currents. They 
control the movements of the main planes so 
that they always bear the same inclination to the 



AEROPLANES 169 

horizontal, and they are also used to elevate the 
machines so as to clear small obstacles. If any 
great increase in altitude is desired, the speed of 
the engine must be increased and the planes driven 
more rapidly through the air, thus giving them more 
lifting power. 

"It may be that in a short time, additional 
balancing planes will not be necessary, as some 
other scheme may be invented that will regulate 
the balance of the aeroplane. Already an Aus- 
tralian inventor, called Roberts, has applied the 
gyroscope to the aeroplane in order to solve the 
problem of making it balance automatically. It 
exerts a balancing force equal to 300 pounds, placed 
18 inches on either side of the centre of gravity. 
The gyroscope is driven by electricity, and controlled 
by a pendulum which swings right or left, according 
to the tilt of the aeroplane. Mr. Roberts is also 
working on a small aeroplane which is to be con- 
trolled by wireless telegraphy. His inventions are 
being tested by the British War Office. There 
are many other inventors on three continents 
busily employed in trying to solve the balance 
problem. 

**A very important matter in the construction 
of the aeroplane is the position of the screw pro- 



170 MECHANICS 

peller. Sir Hiram Maxim advocates placing it 
at the rear of the planes, and this construction is 
carried out in the Wright, Curtiss, Voisin and 
Baldwin-McCurdy machines, while the tractor screw 
is used on the Bleriot, Antoinette, and Roe fliers. 
Sir Hiram's theory is that if the screw is placed 
in front, the backwash strikes the machine, which 
offers a good deal of resistance to the passage of 
the air, and retards action; but if the propeller 
is placed in the rear, the resistance of the machine 
imparts a forward motion to the air with which 
it comes in contact, and the screw, running in air 
that is moving forward, has less slip, and is, there- 
fore, more efficient than the tractor screw. 

"While the construction of the aeroplane is yet 
in an experimental stage, it is progressing quite 
rapidly, and though no definite rules covering 
the whole ground of construction and management 
can yet be laid down, the following points may 
be well considered before any steps are taken in 
making or using any make of aeroplane: (1) 
That it is useless to construct the planes of flat 
vertical section, as much lift is lost in doing so, and 
they are best constructed after the manner shown 
in Figs. 44 and 44a. (2) That the most practical 
aspect ratio is about 6 to 1. (3) That the angle 



AEROPLANES 171 

of incidence of the inclined planes ought to be some- 
where between 1 in 10, and 1 in 20 (i. e,, the angle 
by which they are inclined to the horizontal, the 
forward or entering edge of the plane of course 
being the higher). (4) That a reliable motor, one 
that is immune from involuntary stoppages, is abso- 
lutely essential to prevent accidents. (5) That 
automatic stability of the machine is the theory 
of aeronautics that all inventors should study most 
carefully. 

"The illustration I show here (Fig. 45) repre- 
sents the monoplane in which the Frenchman, 




Fig. 45. Bleriot monoplane 

Bleriot, crossed over the sea from France to Eng- 
land. The thick curved lines, shown at A, exhibit 
the main plane which gives the machine its name 
of "monoplane" — one plane — and B shows the 
rear auxiliary plane, which is also of curved section 



172 MECHANICS 

and curved ends. The plane A has an area of 150 
square feet, and B has an area of 17 square feet, 
while the rudder C has an area of 43^^ square feet. 
The total length of the machine is 25 feet, the sweep 
of the rudder 6 feet 6 inches. The rudder is a 
plane, pure and simple, and may be constructed 

of any light material that is 
strong enough to stand a 
reasonable wind pressure. 




Fig. 46. Plan of Bleriot machine 

The planes must be covered 
on both sides with some 
light fabric, silk preferred, 
and all the framework made 
as light as possible, consistent with safety. 

"The plan I show at Fig. 46 will give you a 



AEROPLANES 173 

good idea of the form of this machine, if you were 
looking from above at it. E is the point where 
the aviator sits, and where the 30 horse-power 
engine is placed. The ends of the planes are rounded 
oflF, and the ends of the rear plane at DD, are made 
adjustable so that the machine may be made easier 
to manage when in motion. 

"All engines used in aeroplanes are of the inter- 
nal combustion type, made purposely for aerial 
flight, and are as strong and as light as it is 
possible to make them. 

"The biplane, or two plane machine, is fitted 
up on somewhat the same lines as the monoplane, 
having two planes one above the other, as I show 
you in Fig. 47. The dark portion A A, shows the 




Fig. 47. Biplane 



positions and curvature of the planes. The plane 
B is called the elevator because it keeps up the 



174 MECHANICS 

head of the machine. C shows the tail with a 
single plane. D is the part containing the mechan- 
ism and the aviator's seat. E shows the vertical 
planes, made of some light fabric stretched over 
a bamboo frame. The propeller is shown at P, 
and it is about six feet in diameter. The two carry- 




Fig. 48. Voisin biplane 

ing wheels, shown at G G, are simply light bicycle 
wheels which tend to ease the landing of the ma- 



AEROPLANES 175 

chine when it comes to the earth. It will be seen 
that machines may differ in the style of construction 
and yet, so long as they contain the principles I have 
described, they will fly with more or less success. 
The illustration, (Fig. 48), shows the plan of the 
biplane, which is somewhat different in arrangement 
from the monoplane. This sketch is of the Voisin 
biplane and shows the tail-piece, something not 
used in machines of the Wright type. The Voisin 
machine is quite popular in Europe, particularly 
in France. It is not very difficult to construct 
or easy to control; at least, it has that reputation. 
"The Santos Dumont monoplane. Demoiselle^ 
shown in Fig. 49, is said to be the smallest and 
lightest known practical machine, and there are 
no patents on it, the inventor having published 
sketches and drawings of all its details. Contrary 
to the usual plan, the aviator, in this machine, sits 
below the motor, so that the propeller blades cut 
across the line of sight; but as it revolves very 
rapidly the vision is not affected. The whole 
machine, when complete, weighs only about 250 
pounds. Its length is about 20 feet and its total 
width over the planes 18 feet, and it is about 7 feet 
6 inches high. It is quite easy to build, as the frame- 
work, or chassis, is fixed to a bent piece of ash or 



176 MECHANICS 

elm — like a sleigh runner — which answers very 
well, because when the machine begins to move 
the rear end rises first. If desired, the frame can 



Propeller 




Warping Win 



Warping Wire 



Staif to Frame 



Stay to Frame 



Cycle Wheel 



Fig. 49. The Santos-Dumont monoplane 

be made so that the whole thing can be taken apart. 
Sockets, like those used on finishing rods, may be 
attached at the joints and junctions to hold the 
structure together. The two spars that consti- 
tute the main support of the planes are formed 
of ash, this having been found the best material 
for the purpose, as it is also for the making of the 
propeller blades. One of the spars should be fixed 
about nine inches from the front edge, and the 
other about twelve inches from the back. Bamboo 
cross pieces are fastened about nine or ten inches 
apart between the two main spars. All is covered 
with oiled silk, applied in two thicknesses. The 



AEROPLANES 177 

area of the main plane is some 115 square feet, and 
that of the tail-piece about 50 square feet. To 
cover all this would require about 400 square feet 
of silk. 

"I have heard it said that aeroplanes are hard 
to manage, difficult to drive, and extremely dan- 
gerous. This is not true entirely, but there is some 
truth in it. An amateur has to go through a 
'course of sprouts' and must learn all about his 
machine before beginning to use it practically. 
Once he becomes master of it and can keep it well 
under control, he need not fear accidents, if he 
does not lose his head, nor venture out in half a 
gale. When we consider the number of experi- 
ments that have been made from time to time 
with imperfect machines, we find that fatal acci- 
dents have been very few, less, indeed, than the 
number recorded in the early stages of automobile 
history. 

"I have been compelled to draw a number of 
the points I have given you from many sources, 
particularly from the writings of Messrs. Fether- 
stonhaugh and Lanchester, which does not detract 
from what I have told you, but rather guarantees 
its correctness. 

"Well, children — it is getting late, but, before 



178 MECHANICS 

bidding you good-night, I think I should finish 
my talk on aeroplanes by showing you how to make 
a small model of a flying machine, if you are not 
too tired to listen further?" 







Fig. 50. A model aeroplane 

"Please, father," said Fred, ** do keep on." 
George, also, wanted to hear more, so Mr. Gregg 
decided to continue. 



AEROPLANES 179 

"I have given you an outline of the reason why 
an aeroplane can be made to rise from the ground 
and navigate the air; but I have not told you of 
all the kinds of machines that can be made to fly, 
for there are many others than those I have spoken 
of. One is the glider, which does not carry an 
engine, but, as its name indicates, glides along in 
the air at a distance not far from the earth. These 
are not capable of travelling very far and, therefore, 
are not likely to come into general use. They 
have to be started either by gliding off a high 
tower, by sliding down a hill or by being propelled 
by hand or towed by some rapidly moving machine. 



Ca/>^fh&« 





Fig. 51. Section model aeroplane 

Some day, perhaps, a machine will be evolved on 
the same or similar lines as the glider, that can be 
propelled by natural forces, but the time is not 
yet. Beside the monoplane and the biplane, there 



RAOtUS 



180 MECHANICS 

is the triplane, constructed on the same lines as 
the other flying planes, that is to say, the three 
planes used on the machine are made the same as 
the planes on the others, each having a convex and 
concave side of diflFerent curvatures. 

"The monoplane which I am about to describe 
and illustrate, and which I show in Figs. 50-51-52, 

can be easily and cheaply 
made, and can be guaran- 
teed to fly, after a little 
experimenting to get the 
correct balance and angle 
of the planes. The frame 
A will first be treated. 
Get two pieces of yellow 
or white pine (the light- 

Kg. 52. Blade of propeUer ^g^ ^^^ ^^^^ ^^gjj^ ^^^_ 

cured wood), cut them to the shape shown, 1 foot 6 
inches long, J^ inch by 1%6 inches in the middle, and 
thickened at the ends to take the screws from the 
end bars B and C (Fig. 50). Take great care to 
make them exactly alike. The end pieces B and C, 
which are 2J^ inches by %6 inch by J^ inch can then 
be screwed to the side pieces A, and a rectangular 
frame is the result. Should the screws split the 
wood in the slightest degree, new pieces must be 





c 






AEROPLANES 181 

made, as the plane is sure to get rough usage in 
falling on the ground a few times. 

" The planes are also made of yellow pine. They 
must be exactly equal to one another in weight, 
one being right handed and the other left. The 
wood must not be more than V22 inch thick, and, if 
possible, even thinner. A large circular chip box 
will be the best thing from which to make these. 
Gum a piece of tracing cloth on top of the planes, 
and allow about 2 inches to overlap at the large 
ends, to twist and glue round the main frame when 
fixing. The cloth will fulfil two useful and nec- 
essary purposes. It will strengthen the planes and 
curve them to a very large extent. This curvature 
is essential to the flight of the machine. A wooden 
block curved to suit, and inclined at about 5 degrees, 
is fixed between the back planes and the frame. 

*'The front or small plane is 8 inches by 3 inches, 
and made in the same way as the others. It must 
be adjustable, and is, therefore, mounted on two 
wooden blocks, 2 inches by 34 inch by J^ inch and 
fastened by means of copper wire which acts as a 
hinge. Four silk cords are fixed to the movable 
end of the plane, two being fastened to nails at the 
rear end of the frame and two to the front, to hold 
the plane at anj'- desired angle. 




182 MECHANICS 

*'The propeller blades (Fig. 52) are made of thin 
aluminum. Two sheets are cut out the same size 
and shape, and placed with their ends overlapping 
(see Fig. 53). A piece of steel wire Viq inch in di- 
ameter is bent and placed between 
them to form the shaft. The whole is 
then fixed in a piece of light copper 
tube, which is slotted by means of a 
Fig. 58. Con- hack saw or fret saw to receive them. 

nections of 

propeller The bladcs are bound crosswise to the 

blade 

tube by means of thm wire or strong 
thread; then twisted to a pitch of about 6 inches. 
It is also advisable to place a washer between 
the copper tube and the end bar of the 
frame. 

'*This method of fixing the propeller blades is 
not the same as that shown in Fig. 50 but it is 
the better way. 

"The drive for the propeller is elastic (a rubber 
band), which, when twisted and released, will 
rapidly revolve the shaft for a short time. The 
best kind to use is the gray variety, and when in 
the form of bands, say % inch by Vi6 inch by 6 
inches, is ready for use without jointing. The wire 
carrying the elastic should be made so that the 
elastic is just in tension when untwisted. 



AEROPLANES 183 

"The monoplane, when complete, should be 
tested without the propeller until it will glide per- 
fectly. The front of the plane will need weight 
added if there is a tendency to somersault; but if 
the back rises ahead of the forward end, more 
weight is necessary there. The best glide to be 
expected is about a 1 in 6 slope. The propeller 
should then be tried, and a flight of 50 or 100 feet, 
or more, should result. If there is a tendency to 
twist, owing to the side pull of the propeller, a 
a screw should be fixed to the end of the plane to 
counteract it. 

''A much longer flight can be given the model, 
if the spring is made so that the tension may con- 
tinue a longer period. Sometimes a rubber at- 
tachment can be applied and twisted so that the 
propeller can be kept running long enough to 
carry the machine a much greater distance than 
here stated. The dimensions of all the parts of 
the machine are marked on the illustrations, so 
that you will find no difficulty whatever in making 
a model monoplane that will fly from the 
start. In the making of little models of this 
kind, you will encounter many things that will 
tax your skill and ingenuity, as amateur work- 
men. 



184 MECHANICS 

"Now, children, I have told you all about aero- 
planes that I intended, though I may take up the 
subject again, when I try to explain the recognized 
theory of flight, and the making and flying of 
kites." 



VIII 

KITES, SUNDIALS, PATENTS 

THE next day, just as Mr. Gregg returned 
from his oflBce, Fred, Jessie, and George 
landed on their new dock from the Car- 
oline. They had been for a sail on the river, 
and Jessie was quite enthusiastic over the trip. 
"Fred was a real good; captain. Why, papa, 
he let me steer the boat all by myself, and taught 
me so well I didn't have any collisions." 

An hour or so later the boys, Jessie, and Mr. 
Gregg, retired to the den. 

After questioning the boys regarding the previous 
talk, to discover if they remembered the main 
points, Mr. Gregg said he would now tell them 
something of kites and kite flying. 

"The highest kite ascent yet recorded was made 
at the aeronautical observatory at Lindenburg, 
(Prussia) on November 25, 1905, 21,100 feet being 
attained. Six kites were attached to one another 
with a wire line of nearly 16,000 yards in length. 
The minimum temperature recorded was 13 degrees, 

185 



186 MECHANICS 

F.; at starting the reading was 41 degrees. The 
wind velocity at the surface of the earth was eigh- 
teen miles an hour, and the maximum altitude 
it reached was fifty-six miles an hour. The previ- 
ous height record by a kite was nearly 1,100 feet 
lower, and it had been reached from a Danish 
gunboat in the Baltic. These ascents were wonder- 
ful, for it is not an easy matter to train a kite higher 
than a given altitude, for several reasons. The 
higher a kite rises the more string it will require, 
and this tends to weight down the plane or kite. 
The wind, too, acting on the string, tends to 
retard the upward flight and to cut short further 
ascent. When an ordinary kite reaches a height 
of 1,200 or 1,500 feet, it is doing very well; and 
few exceed this height. When Benjamin Frank- 
lin angled in the clouds for lightning, his kite did 
not attain an altitude of more than 1,000 feet, 
which was quite sufficient for the purpose he had 
in view. When Franklin flew his kite, he was so 
afraid of ridicule that he took a small boy with 
him to carry the kite and string, in order to pre- 
vent his neighbours from thinking he was going 
*kite flying.' In these days when a man is seen 
flying a kite, people very naturally imagine him 
to be an aeronaut, studying the science for the 



KITES, SUNDIALS, PATENTS 187 

purpose of improving or inventing a flying machine 
of some kind — for which there seems to be ample 
room. 

"The first thing a beginner in the science of 
aeronautics will want to know is, *Why does the 
kite or machine lift itself off the ground?' If 
you take a kite and hold it in an inclined position, 
the wind on the lower side will have a tendency 
to blow it backward; but as it is held by the kite 
string, this movement' is impossible, and so it 
is inclined to rise in the air (see Fig. 54). If we 
construct a large plane and equip it with a motor 
operating a screw which pushes or pulls the plane 






Fig. 54. Science of kite-flying 

along through the air, the result is the same as if 
the plane were anchored, and the wind hits the 
lower surface of the inclined plane, thus forcing 
it up. Also, we find, within certain limits, the 
more you incline a plane the more lift or upward 
thrust will it give; but it will take more power 



188 MECHANICS 

to drive it through the air, and the faster the plane 
is driven through the air the less surface is re- 
quired to support the weight. A matter of great 
importance in the construction is the shape of the 
plane, and the shape of the vertical section through 
the same. The shape of these planes has been 
explained in Figs. 43 and 44, and the reasons were 
given why these shapes were considered the proper 
ones for the purpose. 

"It does not follow," said Mr. Gregg, "that all 
kites should have the same kind of a surface or 
plane, though the flat planes of the toys of our 
school days were all of the flat surface kind; these 
being of various shapes and sizes from the lozenge 
to the square, bow top, octagon, and many others, 
according to the whim or skill of the maker. One 
of the conditions of these planes or flat kites, was 
that each one must have at least one tail attached 
to the bottom of it. This tail was flexible, simply a 
piece of string having paper similar to 'curl papers' 
tied to it at intervals. The tail was a necessity, 
for without it the equipoise would.be impossible. 
In China and Japan, where the natives have been 
kite-flying for more than twenty centuries, they 
make kites that fly and maintain the aerial equipoise 
without having tails hung to them, no matter 



KITES, SUNDIALS, PATENTS 189 

whether the shape be that of a dragon, a lion, or 
an eagle. 

"A kite is simply an aeroplane on a small scale, 
and should be considered as such, as it has a fixed 
fulcrum in the belly band, a constant pressure 
when flying, and an angle which is varied in pro- 
portion to the load it may have to carry. The 
common kite is easily made, but it does not always 
fly as desired; for it seems almost impossible to make 
two kites that will fly in the same manner under 
similar conditions. Box kites are the most reliable, 
and not so very difficult 
to make, as you will dis- 
cover by examining Figs. 
55, 56, and 57 and fol- 
lowing the directions I 
give you. First, procure 
four straight strips of light ^^' 

wood, preferably spruce, 2 ft. 6 in. by ^ in. by 
3^8 ill- J these dimensions should be full (see 
Fig. 55,) Obtain also four other pieces, each 1 
ft. 73^ in. long, but Viq in. wider and thicker 
than the foregoing, and halve their ends to a 
depth of 3^ in. by J^ in., in order that when 
the false end A (Fig. 56) is tightly bound on, these 
cross sticks will firmly grip the long pieces edge- 




190 



MECHANICS 




wise, the sides of the cells being indicated by the 

dotted lines. The long sticks should be notched 

at a distance of 4 in. from their 

ends to receive the forks of the 

cross sticks. 

''The width of the cloth or paper 
cells should be 8 in., and they should 
Fig. 56. Making a be Separated by a distance of 1 ft. 1 
in. or 1 ft. 2 in., their edges being 
bound with fine twine. The easiest way to make the 
cells is to cut two strips of the material, 10 in. wide 
and 4 ft. 8 J^ in. long. Turn over the edges J^ in. 
along each side, and insert fine strong twine! If 
paper is used, glue the fold; if cloth, stitch the 
hem. When completed, either glue or stitch the 
ends of the strip with a ^ in. lap, so as to form a 
continuous band. By folding, divide this accurately 
into four equal parts and at 
each of the creases glue one of 
the long sticks edgewise (see Fig. 
56). When dry, the whole can 
be put together and the flying 
line attached, without a bridle, 
as in Fig. 55. For additional 
clearness an enlarged detail of one end of the kite 
is shown at Fig. 57. 




Fig. 57. Single box kite 



KITES, SUNDIALS, PATENTS 191 

"It is advisable in all cases to make the cross 
pieces a trifle too long, to insure their straining 
the band tightly. They may also be shortened 
by cutting away the shoulder formed by the halving. 

"These kites are easy to fly. Avoid an enclosed 
space, where the wind whirls in invisible eddies; 
having let out 20 yds. or 30 yds. of line, get some 
one to throw up the kite in the usual fashion. If 
several large kites are sent up in tandem, steel 
wire should be used. 

"Another kind of a kite, known as the cellular 
kite is shown in Fig. 58. This is made by forming 
two square frames N. O., divided into nine compart- 




Fig. 58. Square cellular kite 

ments each and connected together by a light rod 
at r, the fulcrum or string being at P, the air pressure 
at T. The whole forms a good, strong kite, but 
it is not able to carry much weight, on account of 
the equipoise being self adjusted in accordance with 



192 MECHANICS 

the constant pressure and surface. The equipoise 
is due to the current being cut by the edges a a\ 
and diverted into the cellular divisions of each 
area. This being the case, any upward or down- 
ward tendency of a a\ would be counterbalanced 
by the effect on the other side and the kite would 
naturally adjust itself on the opposite side. We 
are not dependent upon any particular shape for 
obtaining a good serviceable kite — like the plane 
made kite, the cellular one may be of any shape. 
I show you one here, at Fig. 59, having a circular 
rim, with thin tubes inserted in such a manner that 

^^^ the current of wind 

^ff^^^\ i^W^^^\ will rush through when 
1-1 R. ^^m^\\—\ _ ^^ machine is in the 

air. The two portions, 
A and B, are held to- 

Fig. 59. Circular cellular kite ,i i i • 

getner by a rod m a 
similar manner to the square kites, and the cord 
or fulcrum is fastened to the rod at R. 

"A number of kites may be sent up at once, all 
attached to the same string, if properly adjusted. 
Here are six square cellular kites looped together, 
shown at Fig. 60. They may be made of any 
suitable size, but need not be all of one size, though 
each pair would be better if made the same size* 





KITES, SUNDIALS, PATENTS 193 

They may be looped up, as shown, and the point 
S may be loaded lightly; it will help to steady the 
kite and keep it from sway- ^. 
ing. 

"A peculiar kite, called 'a 
war kite,' is very popular in 
some parts of Europe, and 
in some parts of our country 
also. It is easily made and ^S' ^^' Group of kites 
gives good results. It is on the principle of the 
' cellular 'or ' box 'kite, being cubical or box shaped, and, 
when used for carrying weights, usually has several 
cells built together, or several kites may be coupled 
when a heavy load, such as that of a man, is to be 
raised. These kites are made of light wood or 
cane covered with nainsook or fine cotton, and 
strengthened with cross pieces which hold the 
frames tight and keep the kite in shape. They 
can be taken to pieces and the covering material 
rolled up so that they occupy very little space. 
Two forms of box kites are shown in Figs. 61 and 
62, and it will be seen that an attachment is made 
each side of the frame. This is fine steel wire, 
very light compared with its strength, wound on 
a drum by means of a small engine. Large kites 
of the ordinary form can be used for the same 



194 MECHANICS 

purpose, but their lifting power is not equal to that 
of the box kite. A small box kite is used for 
taking photographs, a camera being carried by a 
separate wire connection to the attachment wire. 





Fig. 61. Sextuple kite Fig. 62. War kite 

and the shutter released at the proper time by an 
ingenious arrangement, similar to the pieces of 
paper called ' messengers ' which boys used to 
send up on the cords of ordinary kites. This kite 
is a little more expensive to make than most of those 
shown, but it gives an excellent result when 
properly handled. 

"In making kites of any kind, the lightest ma- 
terials consistent with sufficient strength, should 
be employed. The frames should be split bamboo 
or cane. The joints may be lashed together with 
fine wire or silk thread, and the envelope in each 
case should be fine silk or similar material that 



KITES, SUNDIALS, PATENTS 195 

would be close, light, and strong, These qualities, 
in all sorts of kites and aeroplanes, are absolutely 
essential to accomplish the best results. 

** Before leaving the subject of aeronautics, I 
think it would not be amiss to tell you something 
of bird flight. There are different modes of flying, 
just as men have different gaits in walking or run- 
ning. 

"Rapid wing movement does not always imply 
speed in flight, any more than does rapid leg move- 
ment imply speed in walking or running. With 
us it is the length of the stride that tells ultimately. 
What tells, correspondingly, in the flight of the 
bird is not known. 

** Speaking broadly, long- winged birds are strong 
and swift fliers; short-winged birds are feeble 
in flight. When we consider that a cumbrous, 
slow-moving bird like the heron moves its wings 
twice per second when in flight, it is evident that 
many birds have a very rapid wing movement. 
Most small birds have it, combined with feeble 
powers of flight. The common wren and the chip- 
ping sparrow, for instance, have a flight like that 
of a young bird. 

"What can give one more exquisite pleasure 
than to watch seagulls swooping round the edge 



196 MECHANICS 

of a cliflf, to see them drift down wind with wings 
motionless, then suddenly dart downward, turn 
to meet the breeze, and beat up against it with all 
their ingenuity and skill? 

"The beauty of a ship depends on the way it 
glides through the water. Watch a liner, and you 
can see that it is being driven by its screws, but 
look at a racing yacht: there is no sense of effort 
whatever. She seems to move like a bird, by 
natural means. 

''Here is the secret of the beauty of the aero- 
plane. It seems to be completely master of the 
element in which it moves. It flies with no visible 
effort and at a little distance one could imagine it 
endowed with magic power, moving by natural 
force, like a bird. 

"All the early attempts at flying were made on 
the theory of wing motion, and the failures resulting 
were doubtless due to careless study of what nature 
could teach. There was a great deal more to be 
learned from nature than from mathematics. An 
examination of the different types of birds testi- 
fies, among other things, to their rigid backs, and 
to the fact that nearly all their bones are hollow 
and have air cavities. An erroneous deduction had 
been drawn from this that the hollows were purely 



KITES, SUNDIALS, PATENTS 197 

for the sake of lightness, and that the cavities 
were for hot air to make the bird Hght when it 
wanted to fly. The amount of Hghtness so ob- 
tained, however, was so small as not to be worth 
consideration. The passages are simply reservoirs 
for air, and they allow the bird more energy than 
a less freely breathing animal. The wing of the 
bird does a double duty: it is an aeroplane and a 
propeller combined. The valvular action has noth- 
ing at all to do with the flight. Some explanation 
of how a sparrow can rise from the gutter to the 
eaves may be seen by the difference in the con- 
struction of its wings from those of the swallow, 
which cannot rise from the ground like a sparrow, 
but has to get initial velocity. The swallow, how- 
ever, has much more mastery over its movements 
in the air than the sparrow has. These, and many 
other things in connection with bird flight, under 
proper methods of scientific investigation, may 
show us the whole theory of aviation. I am in- 
clined to think that scientific men will soon be able 
to solve the problem, and to give us better control 
of the coming aeroplanes, or even direct their flight 
by the aid of electric waves or other natural forces. 
"In kite-flying, it is well to know something of 
the wind and its pressure, and, in this connection. 



198 MECHANICS 

the following short table will give some idea of 
the force exercised on objects in its path: A light 
air current presses 0.004 lbs. per square foot. 



Light wind has a pressure of 
Light breeze 
Moderate breeze 
Strong breeze . 
Moderate gale 



. 0.125 lbs per sq. foot 

. 0.246 lbs. per sq. foot 

. 0.406 lbs. per sq. foot 

. 2.00 lbs. per sq. foot 

. 2.98 lbs. per sq. foot 



**This last should be the limit, as a kite or aero- 
plane of any kind will find it hard to manoeuvre 
in a breeze stronger than a moderate gale. Of 
course, there are winds sometimes that have a 
velocity of 60 to 75 miles an hour, and a pressure 
of over 40 pounds to the square foot, but these 
would prove disastrous to any kind of a flying 
machine, if it was in action.' * 

"Father," asked Fred, *'how can one tell the 
velocity of the wind, without one of those expensive 
machines I see at the weather office, an anemometer, 
I think it is called.?" 

"I am glad," said the father, "that you have 
noticed those and other instruments for gauging 
and foretelling weather conditions. It is an indica- 
tion that you keep your eyes open when you visit 
such places, and to learn by observation is almost 
as effectual as to obtain knowledge by experience. 



KITES, SUNDIALS, PATENTS 199 

I have in mind a very simple contrivance you can 
make yourself, for measuring wind pressure from 
a couple of ounces to four pounds to the foot. I 
will make a sketch of it, which I am sure you will 
understand. 

"It consists of a light pine or cedar wood frame 
on a strong stand, supporting on a centre two bent 
wires, carrying at one end a 3-in. square of thin 
wood. A, and on the other a thin bar of wood, to the 
centre of which is attached a fine string tied to a 
spring balance scaled to }/$ of an ounce and up to 4 
ounces (Fig 63). As the 
square of 3 inches is the 16th 
of a foot, each ounce on the 
spring is equal to 1 lb. pres- 
sure on the square foot. 
The latter balance slides in 
the V-frame at the back so 
as always to keep the square 
parallel to the face of the 
frame, whether the wind is 
strong or light, and the bal- 
ance must be slidden in or 
out until the face of the square is so placed 
before registering the force of the wind. By at- 
tention to this it will register very truly up 



^ 



\ 



Fig. 63. Windgauge 



200 MECHANICS 

to 4 lbs., which is the extent of an ordinary spring 
balance. There is also a front view, a side view, 
and a bird's-eye view, also one of the bent wires 
and the 3-inch square. I think this requires no 
further explanation." 

Fred was satisfied with the description of the^ 
register and promised to make one at an early date. 

The following evening when they were all sit- 
ting on the river bank, Fred suddenly asked his 
father if it was difficult, or costly, to secure patents. 
He wanted to know, because he had been thinking 
of making a kite on a new principle — that of a 
funnel, and he was so sure it would prove a success 
that he would like to have it patented. >| ; 

Mr. Gregg thought the scheme rather an ambi- 
tious one, but, while he could not see it as Fred 
did, he determined not to say anything that would 
be likely to discourage the boy. So he explained, 
as well as he could, the patent laws: "In order to 
apply for a patent it is necessary to file in the Patent 
Office at Washington, D. C, a petition, affidavit 
of invention, drawings, and specifications, all of 
which must be prepared in legal form and in ac- 
cordance with official rules and practice of the 
office. 

*'This can best be done by a reliable attorney 



KITES, SUNDIALS, PATENTS 201 

but an applicant should understand some of the 
requirements as well. 

*'The Patent Office does not require a model to 
be furnished in order to apply for a patent, but if 
the attorney is not near enough to see the one made 
by the inventor, then one should be sent him, 
unless good photographs and drawings can be 
supplied. 

"Since the drawing attached to the specifications 
and claims is to be on a sheet of a special size, 
no attention need be paid to having the original 
sketches of a uniform size. When ready to apply 
for a patent, secure as much evidence as possible 
of the reliability of some attorney you have heard 
of and consult him about the matter, explaining 
as much as is necessary for him to prepare an out- 
line that will suffice for a preliminary search through 
the records in the Patent Office to see that no inter- 
ference will take place should the application be 
made. ^ 

"This usually costs $5.00, and an attorney often 
supplies copies of existing patents that look the 
most like the one in question. 

"If it is thought that there will be no interference, 
the case is then prepared for the examiners, and 
the application duly made. 



202 MECHANICS 

**The drawings should be made and lettered, so 
that the specifications can be written up, including 
the proper reference to the different parts. 

"The drawings should be made upon paper stiff 
enough to stand in a portfolio, the surface of which 
must be calendered and smooth. The best kind is 
patent oflBce bristol, though there is a style on 
the market printed with margin and headings all 
ready for use, but the surface is not of the best. 

"The size. of the sheet on which a drawing is 
made should be exactly 10 x 15 inches with margin 
lines one inch from all the edges, leaving a clear 
space of 8 X 13 inches. 

"One of the smaller sides is regarded as its top, 
and measuring downward from the margin, or 
border line, a space of not less than 13^ inches is to 
be left blank for the insertion of title, name, number 
and date, to be put in by the patent officials. 

"All drawings must be made with the pen only, 
using the blackest India ink. Every line and 
letter, including the signature must be absolutely 
black. 

This applies to all lines, however fine, to shading 
and to lines representing cut surfaces in sectional 
views. All lines must be clean, sharp, and solid, 
and they must not be too fine or crowded. 



KITES, SUNDIALS, PATENTS 203 

"Surface shading, when used, should be left very 
open. Sectional shading should be by oblique 
parallel lines, which may be about one-twentieth 
of an inch apart. Drawings should be made with 
the fewest lines possible consistent with clearness, 
for the drawings are subjected to photographic 
reduction, which decreases the space between the 
lines. 

"Shading (except on special views) should be used 
only on convex and concave surfaces, and there 
sparingly, or it may be dispensed with if the draw- 
ing is otherwise well made. 

"The plane on which a sectional view is taken 
should be indicated on the general view by a broken 
or dotted line. 

"Heavy lines on the shade sides of objects should 
be used, except where they tend to thicken the 
work and obscure the reference letters. 

"The light is always supposed to come from the 
upper left hand corner, at an angle of forty-five 
degrees. 

"Imitations of wood or surface graining should 
not be attempted. 

"The scale to which a drawing is made ought 
to be large enough to show the mechanism without 
crowding, and two or more sheets should be used 



204 MECHANICS 

if one does not give sufficient room to accomplish 
this end; but the number of sheets must never be 
increased unless it is absolutely necessary. 

"Sometimes the invention, although constituting 
but a small part of a machine, has to be repre- 
sented in connection with other and much larger 
parts. In a case of this kind, a general view on 
a small scale is recommended, with one or more 
of the invention itself on a much larger scale. 

"Letters or figures may be used for reference, 
but they should be well made, and when at all 
possible should not be less than one eighth of an 
inch in height, that they may bear reduction to 
one twenty-fourth of an inch; or they may be 
much larger when there is sufficient space. 

"Reference letters must be so placed in the close 
and complex parts of a drawing as not to interfere 
with a thorough understanding of the same, and 
to this end should rarely cross or mingle with the 
lines. 

"The illustrations on pages of current topics 
under the head of new patents show the manner 
of putting in the reference lines from the letters 
to the part indicated. 

"These are carried out some distance, but if 
placed on the face of the object where sectioned, 



I 



KITES, SUNDIALS, PATENTS 205 

a blank space should be left in the shading for the 
letter. 

"If the same part of the invention appears in 
more than one view, it should always be represented 
by the same letter. 

"Great care should be exercised in the matter 
of drawings, or they will be returned to the appli- 
cant, but, at his suggestion and cost, the officials 
will make the necessary corrections. 

"The time required to procure an allowance 
of a patent averages from six weeks to two months. 

"United States patents are granted for a term 
of seventeen years, and cannot be extended. The 
patent remains good whether the invention is 
worked or not, and no additional payments are 
required beyond the cost of first taking out the 
patent. Patents are not subject to taxation. Re- 
issues of patents are granted whenever one is in- 
operative or invalid, by reason of a defective or 
insufficient specification, or by reason of the patentee 
claiming more than he had a right to claim as new, 
provided the error arose bjrinadvertence, accident, or 
mistake, without fraudulent intent. A fee of $30.50 
must be forwarded upon application for patent. 

"As stated before, a patent is obtained by a 
petition to the Commissioner of Patents accom- 



206 MECHANICS 

panied by a description, including drawings and a 
model, when the invention will admit of these. A 
fee of $15 is required when the application is made, 
and a further fee of $20 when the patent is issued. 
Postage on model is at the rate of 1 cent per ounce. 

"A patent for a design is granted to any person 
who has invented or produced any new and origi- 
nal design for the printing of woollen, silk, cotton, 
or other fabrics; any new and original impression, 
ornament, pattern-print, or picture to be printed, 
painted, cast, or otherwise placed on or worked 
into any article of manufacture; or any new, 
useful, and original shape or configuration of any 
article of manufacture, the same not being known 
or used by others before this invention or produc- 
tion thereof, or patented or described in any printed 
publication, upon payment of the duty required 
by law, and other required proceedings the same 
as in cases of inventions or discoveries. These 
are granted for three and one-half years, seven 
years or fourteen years, for which the respective 
fees of $10, $15, and $30 are paid the government. 

"A caveat is a provisional protection to any per- 
son who has thought of an invention and desires 
the time to complete or perfect the same. It is 
procured at an expense of $10, and runs for one 



KITES, SUNDIALS, PATENTS 207 

year with the permission of renewal from year 
to year. 

"In Canada the patent oflSce is a branch of the 
Department of Agriculture, and the Minister of 
Agriculture for the time being is the Commissioner 
of Patents. 

"Any intending applicant for a patent who has 
not yet perfected his invention, and is in fear of 
being despoiled of his idea, may file in the patent 
office a description of his invention so far, with, 
or without plans, of his own will, and the Com- 
missioner, on payment of the prescribed fee, shall 
cause the said document, which shall be called a 
caveat, to be preserved in secrecy, and, if appli- 
cation is made by any other person for a patent 
interfering in any way therewith, the Commis- 
sioner shall forthwith give notice, by mail, of such 
application to the person filing such caveat, who 
shall, within three months thereafter, if he wishes 
to avail himself of the caveat, file his petition, and 
take the other steps necessary on application for 
a patent. The apphcation for the patent must 
be made within one year from the fifing of caveat, 
otherwise the Commissioner is relieved from the 
obligation of giving notice. 

"The following fees are payable: Full fee 



208 MECHANICS 

on patent for 18 years, $60.00; partial fee for 12 
years, $40.00; partial fee for 6 years, $20.00; 
on filing caveat, $5.00; on registering assignment 
patent, $2.00; for copy of patent, with specifica- 
tion, $4.00. 

**The disbursements for filing an application in 
Great Britain are $25.00; France, $20.00; Ger- 
many, $5.00, and $7,50 before issuing patent; 
Australia, $20.00; Russia, $75.00; British India, 
$20.00. The German and French patents cover 
not only Germany and France but their colonies 
also. The Russian patent extends to all of the 
Russian possessions. 

''The disbursements for filing an application in 
the Australian states, namely, Queensland, Vic- 
toria, New South Wales, South Australia, Western 
Australia and Tasmania are $5.00 on filing the 
application, $10.00 on allowance of same, and 
$25.00 for preparation of the sealing of patent; 
New Zealand, $20.00;. Mexico, $75.00; Natal, 
$50.00; Japan, $75.00; Jamaica, $150.00." 

This talk on patents was quite interesting to 
Fred, and very instructive to George, and they 
thanked their father for it. 

"Boys," he said to them next morning, "why 
not try your hands on a sundial .^^ You will find it 






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KITES, SUNDIALS, PATENTS 209 

easy to make, and if properly set up it will keep 
accurate time. There is a nice place for one near 
the bridge on the new grounds, as there is a stump 
there, the top of which can be cut off smooth, and 
it stands out full in the sun. 

'*Go to our jeweller in the city and get him to 
give you an old tin clock-dial, like the one shown 
in Fig. 64. If you cannot get one, make a dial out 
of cardboard yourself, printing the hours in ink. 
Slit the dial from the cen- 
tre to a point directly un- 
derneath the number 12, if 
you have Arabic numerals 
on your dial. 

"Then cut out a triangu- 
lar blade or gnomon, like 
the one shown. If your 
dial is of tin, make the 
blade of tin, or cardboard 
if your dial is of cardboard. 

"Insert the blade in the slit of the dial and se- 
cure it to the top of the stand you have selected — 
with tacks if your dial is cardboard, with small 
nails if it is tin. Then your sundial will be com- 
pleted and ready for business. ^ 

"At 12 o'clock, there will be only the shadow 




Fig. (54. Sundial 



210 MECHANICS 

of the thin edge of the blade over the dial, but as 
the sun moves, so will the shadow, so as to tell 
always the correct time of day. You will find this 
not only a useful but a quaint and artistic addition 
to the grounds, and not at all expensive." 

"Papa," said George, " mamma wants a flower- 
bed made in the front garden, and she would like 
to have it an oval or elliptical shape. I have 
promised to make it for her, but I do not know 
how to make the shape, and I wish you would tell 



me." 



"Certainly, my boy, I will show you. It can 
be done easily with a string and two wooden pegs. 
Follow the lines I make on the blackboard. First 
we must decide on the length and width of the oval 
or rather ellipse required. Then draw two straight 
lines, A B and C D, Fig. 65, equal to the two axes, 
and bisect or halve each at right angles. Set off 
from C half the length of the great axis at E and 
F, which are the two focii of the ellipse. Take 
an endless string, as long as the three sides of the 
triangle, C E F, fix two pins or nails in the two 
focii, one at E and one at F. Lay the string around 
E and F, stretch it with a marker G, and it then 
will describe the desired ellipse. 

"This is not at all difficult, and will answer for 



KITES, SUNDIALS, PATENTS 211 

any kind of an ellipse, short or long, narrow or wide. 

This is called the "gardener's method." The main 

thing is to get the two 

points, E and F. This 

distance is always half 

of the long diameter A 

B, no matter what that 

may be, and this distance 

is then transferred by 

taking C as the starting 

point, measuring from there until the other point 

of measurement cuts the long diameter, as at E 

and F. 

"The ellipse has many peculiar and useful quali- 
ties, which you will doubtless discover before 
long." 




Fig. 65. Drawing an ellipse 



TIDES 

NOW, papa!" said Jessie the following even- 
ing, after Mr. Gregg and the family had 
strolled down to the river bank to enjoy 
the cool air, "you promised to tell me about the 
tides and the moon — when you could spare time. 
Haven't you got time now?" 

"I may as well say all I intended now, my dear, 
and leave some other matters for future considera- 
tion. As this subject may tax your patience, I 
hope you, Fred, and George, will give me your 
earnest attention. 

"In order to have a clear understanding of the 
movements of the tides and their supposed causes, 
you must know something of the moon's influence 
over them; as this knowledge will aid you very much 
in remembering what I am about to say. 

"The earth is a globular body. One reason for 
this belief, among many others, is that sailors or 
others who go to sea soon observe that as they sail 
from shore, the lower portions of mountains, steeples 

212 



TIDES 213 

or other high objects, are gradually lost sight of 
while the higher parts do not so soon disappear. 
Persons on shore first notice the upper portions of 
masts, and the smoke-stacks of approaching vessels, 
which would not be the case, if the earth were a 
plane, but is very easily accounted for, on the sup- 
position of its being a sphere, as you can readily 
understand by looking at Fig. 66, Several naviga- 
tors have sailed completely round the earth by 
continuing in the same direction, and coming at 
last to the same place from which they started. 




Fig. 66. Proof of earth's rotundity 

The earth, however, is not a perfect sphere but a 
spheroid like an orange; having its equatorial 
longer than its polar diameter or axis. It is flattened 
at the poles, and more protuberant at the equator. 
The diameter at the equator is 7,977 miles, and at 
the poles 7,940, a diflference of 37 miles. 

"You know that the cause of day and night is the 
rotation of the earth on its own axis. It shows a 
large portion of its surface to the sun continually, 
or in other words, the sun is always shining on some 



214 MECHANICS 

portion of the earth's surface. You are also aware 
of the earth and its satellite, the moon, both being 
held in their orbits by the sun's attraction, the 
moon being further kept in her orbit by the attrac- 
tion of the earth. Now the earth is composed of 
three main elements, air, water, and land, and if 
you consider, for a moment, that the daily rota- 
tory movement of the earth is something like 1,000 
miles an hour, this rapid speeding through space 
must have some effect on air and water in assisting 
or retarding their flow. 

"Nature has divided time, and man has named 
and subdivided it into years, months, and days. 
The natural month, however, does not consist of 
four weeks, nor is the natural year made up of the 
twelve calendar months given us by the almanac. 
A natural, or lunar, month is the time the moon takes 
to perform her journey round the earth, which is 
27 days 7 hours, and 43 minutes; this is called the 
periodical month, while the average calendar or 
synodical month consists of 29 days 12 hours and 
44 minutes. The light of the moon is borrowed 
from the sun, for if it were her own light, she would 
shine all the time and not be subject to her present 
phases. The moon is seen by means of the hght 
which comes to it from the sun being reflected from 



TIDES 215 

it. Its changes, or phases, depend upon its rela- 
tive position to the earth and the sun. When 
the moon is in opposition to the sun at A (Fig. 67) 
the lighted side is turned toward the earth, as 
A, and it appears full. When the moon is in con- 
junction at E with the sun, its dark side is turned 
toward us, and it is in- 
visible, as at e. As it pro- 
ceeds in its orbit, as at 
F, a small part of the 
light side is seen, and 
then we have what is 
called a new moon; and 
we continue to see more 
and more of the light 
side, as the moon ap- 
proaches at G and H, 
to the state of opposition 
or full moon. The wan- ^s- ^'^- ^^^^es of the moon 
ing or decreasing of the moon takes place in the 
same manner, but in a contrary order. The 
earth must perform the same office to the moon 
that the moon does to us; and it will appear to the 
inhabitants of the moon (if there be any), like a very 
magnificent moon, being to them about thirteen times 
as large as the moon is to us and it will also have 




216 MECHANICS 

the same changes or phases. Hence it is evident, 
that one half of the moon is never in darkness, the 
earth constantly affording it a strong light, during 
the absence of the sun; but the other half has a 
fortnight's light and darkness by turns. 

"The moon's orbit is elliptical, and she also rotates 
on her axis and takes the same time to circle the earth, 
consequently every part of the moon is successively 
presented to the sun, yet the same hemisphere is 
always turned to the earth. This has been disco- 
vered by observation with good telescopes. The 
length of a day and night in the moon is more than 
twenty -nine and a half days of ours; and while her 
year is the same length as ours, being measured 
by her journey around the sun with us, so she has 
but twelve days and a third in a year. Another 
remarkable circumstance is that the moon's hemis- 
phere next the earth is never in darkness, for when 
it is turned from the sun, it is illuminated by light 
reflected from the earth in the same manner as 
we are lighted by a full moon. The other hemis- 
phere of the moon however, has a fortnight's light 
and darkness by turns. If there are inhabitants 
in the moon, which is doubtful, the satellite will 
appear to them to be about thirteen times as 
large as the moon does to us, and when it is 



TroES 217 

new moon to the earth, it is full earth to the 
moon. 

*' There are many things regarding our relation- 
ship to the moon that would be of interest, if I had 
time to explain them, such as eclipses, the moon's 
I surface as seen through telescopes, its supposed 
influence on the weather, etc., but I fear too much 
moon might prove tiresome. Beside I have shown 
you sufllcient to enable you to understand the 
relationship existing between the moon and the 
tides, generally accepted as the true theory. 

''If we agree that the tides are occasioned by the 
attraction of sun and moon, more particularly the 
latter, we can readily understand their dependence 
on some known and determinate laws. Our alma- 
nacs published long in advance give the exact time of 
high water at any prominent port in the United 
States on the morning and afternoon for every day 
in the year; and seafaring men can tell you when 
the tide will be high or low, notwithstanding the 
fact that these movements are not fixed. They 
know from experience that the time of ebb and 
flow varies about three quarters of an hour each 
day. 

''The first person who clearly pointed out the 
accepted cause of the tides and showed its agree- 



218 MECHANICS 

ment with the eflFects, was Sir Isaac Newton. He 
discovered a relationship between the moon and the 
tides, and by the apphcation of his new principles 
of geometry, the attraction was made clear. 

"The ocean, it is well known, covers more than 
one half the globe; and this large body of water is 
found to be in continual motion, ebbing and flowing 
alternately, without the least intermission. For 
instance, if the tide is now at high water mark, in 
any port or harbour which lies open to the ocean, 
it will presently subside, and flow regularly back 
for about six hours, when it will be found at low 
water mark. After this it will again gradually 
advance for six hours; and then recede in the same 
time to its former situation, rising and falling alter- 
nately twice a day, or in the space of about 
twenty-four hours. The interval between its ebb 
and flow is not precisely six hours, for there is a 
little difference in each tide; so that the time of 
high water does not always happen at the same hour, 
but is about three quarters of an hour later each day, 
for about thirty days, when it again recurs as before. 
For example, it is high water to-day at noon, it 
will be low water at eleven minutes after six in the 
evening; and, consequently, after two changes 
more, the time of high water the next day will be 



TIDES 219 

at about three quarters of an hour after noon; the 
day following it will be at about half an hour after 
one, the day following that at a quarter past two, 
and so on for thirty days; when it will again be found 
to be high water at noon, as on the day the observa- 
tion was first made. This exactly answers to the 
motion of the moon which rises every day about 
three quarters of an hour later than upon the pre- 
ceding one, and by moving in this manner round the 
earth, completes her revolution in about thirty 
days, and then begins to rise again at the same time 
as before. 

'*To make the matter still plainer; suppose, at 
a certain place, it is high water at three o'clock in 
the afternoon, upon the day of the new moon; the 
following day it will be high water at three quarters 
of an hour after three; the day after that at half an 
hour past four; and so on till the next new moon, 
when it will again be high water exactly at three 
o'clock, as before. By observing the tides contin- 
ually at the same place, they will always be found 
to follow the same rule; the time of high water, 
upon the day of every new moon, being exactly at 
the same hour, and three-quarters of an hour later 
every succeeding day. 

"The change of the tides is in such exact con- 



220 MECHANICS 

formity with the motion of the moon that, indepen- 
dently of mathematical calculations, a thoughtful 
person would certainly be induced to look to her 
as their cause. 

'*The waters at Z, on the side of the earth, A, B, 
C, D, E, F, G, H, next the moon M, (Fig. 68) are 
more attracted by the moon than the central 
parts of the earth, O, and the central parts are more 
attracted by her than the waters on the opposite 
side of the earth at n; and therefore the distance 

between the earth's cen- 
tre and the waters on 
its surface under and 
opposite to the moon 
will be increased. Let 
there be three bodies 
at H, O, and D ; if they 
are all equally attracted 
by the body M, they will 
all move equally fast toward it, their mutual 
distance from each other continuing the same. 
If the attraction of M is unequal, then that body 
which is most strongly attracted will move 
most quickly and will increase its distance from the 
other body. M will attract H more strongly than 
does O, by which the distance between H and O 




Kg. 68. Theory of the tides 



TIDES 221 

will be increased, and a spectator on O will per- 
ceive H rising higher toward Z. In like manner, 
O being more strongly attracted than D, it will 
move farther toward M than D does; consequently 
the distance between and D will be increased; 
and a spectator on O, not perceiving his own motion, 
will see D receding farther from him towards N; 
all effects and appearances being the same, whether 
D recedes from O, or O from D. 

"Suppose now there is a number of bodies, as 
A, B, C, E, F, G, H, placed round O, so as to form a 
flexible or fluid ring; then, as the whole is attracted 
toward M, the parts at H and D will have 
their distance fromO increased; whilst the parts at B 
and F being nearly at the same distance from M as 
O is, these parts will not recede from one another; 
but rather by the oblique attraction of M, they will 
approach near to O. Hence, the fluid ring will 
form itself into an ellipse Z, n, L, N, whose longer 
axis n, O, Z, produced will pass through M, and its 
shorter axis B, 0, F, will terminate in B and F. Let 
the ring be filled with fluid particles, so as to form 
a sphere round O ; then, as the whole moves toward 
M, the fluid sphere being lengthened at Z and n 
will assume an oblong or oval form. If M is the 
moon, the earth's centre. A, B, C, D, E, F, G, H, the 



222 MECHANICS 

sea covering the earth's surface, it is evident, by the 
above reasoning, that whilst the earth by its gravity 
falls toward the moon, the water directly below 
at B will swell and rise gradually toward her; also 
the water at D will recede from the centre, (strictly 
speaking, the centre recedes from D) and rise on the 
opposite side of the earth; whilst the water at B 
and F is depressed, and falls below the former level. 
Hence as the earth turns round its axis from the 
moon to the moon again in 24^ hours, there will 
be two tides of flood and two of ebb in that time, 
as we find by experience. 

*'That this doctrine may be still more clearly 
understood, let it be considered that, although the 
earth's diameter bears a considerable proportion 
to the distance of the earth from the moon, yet 
this diameter is almost nothing when compared to 
the distance of the earth from the sun. The differ- 
ence of the sun's attraction, therefore, on the sides 
of the earth under and opposite to him, will be much 
less than the difference of the moon's attraction 
on the sides of the earth under and opposite to her; 
and, for this reason, the moon must raise the tides 
much higher than they can be raised by the sun. 
The effect of the sun's influence, in this case, is 
nearly three times less than that of the moon. 



TIDES 223 

The action of the sun alone would, therefore, be 
sufficient to produce a flow and ebb of the sea; but 
the elevations and depressions caused by this means 
would be about three times less than those produced 
by the moon. 

"The tides, then, are not the sole production of 
the moon, but of the joint forces of the sun and moon 
together. Or, properly speaking, there are two 
tides, a solar one and a lunar one, which have a 
joint or opposite effect, according to the situation 
of the bodies which produce them. When the actions 
of the sun and moon conspire together, as at the time 
of new and full moon, the flow and ebb become more 
considerable; and these are then called the spring 
tides. But when one tends to elevate the waters 
while the other depresses them, as at the moon's 
first and third quarters, the effect will be exactly 
the contrary: the flow and ebb, instead of being 
augmented, as before, will now be diminished; and 
these are called the neap tides. 

''To explain this more completely, let Fig. 69 
represent the sun, Z, H, R, the earth, and F and C 
the moon at her full and change. Then, because 
the sun S, and the new moon C, are nearly in the 
same right line with the centre of the earth O, 
their actions will conspire together, and raise the 



1 



224 MECHANICS 

water above the zenith Z, or the point immediately 
under them, to a greater height than if only one of 

these forces acted alone. 
But it has been shown that 
when the ocean is elevated to 
the zenith Z, it is also elevated 
to the opposite point, or 
nadir, at the same time; and 
therefore in this situation of 
the sun and moon, the tides 
will be augmented. And again, 
whilst the full moon F raises 
the waters at N and Z, direct- 
ly under and opposite to her, 
the sun S, acting in the same 
right line, will also raise the 
waters at the same point Z 
and N, directly under and op- 
posite to him. Therefore, in 
this situation also, the tides 
will be augmented; their joint 
effect being nearly the same 
at the change as at the full; 
and in both cases they occasion 
what are called the spring tides. 

"On this theory, the tides ought to be highest 




Fig. 69. Attractions of the 
moon 



TIDES 225 

directly under and opposite to the moon; that is, 
when the moon is due north and south; but we find 
that in open seas, where the water flows freely, the 
moon is generally past the north and south meridian 
of the place where it is high water. The reason is 
obvious; for though the moon's attraction were 
to cease altogether when she was past the meridian, 
the motion of ascent communicated to the water 
before that time would make it continue to rise for 
some time after; much more must it do so when 
the attraction is only diminished. A little impulse 
given to a moving ball will cause it still to move 
farther than otherwise it could have done; and 
experience shows that the day is hotter about three 
in the afternoon than when the sun is on the meri- 
dian, because of the increase made to the heat 
already imparted. 

'* Tides do not always answer to the same distance 
of the moon from the meridian at the same place, 
but are variously affected by the action of the sun, 
which brings them on sooner when the moon is 
in her first and second quarters, and keeps them 
back later when she is in her third and fourth; 
because, in the former case, the tide raised by the 
sun alone would be earlier than the tides raised by 
the moon; and in the latter case, later. 



226 MECHANICS 

''The sea, being put in motion, would continue 
to ebb and flow for several times, even though the 
sun and moon were annihilated, and their influences 
at an end, on the same principle that if a basin of 
water is once agitated, the water will continue to 
move for some time after the basin is left to stand 
still. A pendulum, put in motion by the hand, 
continues to make several vibrations without any 
new impulse. When the moon is at the equator, 
the tides are equally high in both parts of the lunar 
day, or time of the moon's revolving from the 
meridian to the meridian again, which is 24 hours 
50 minutes. But as the moon declines from the 
equator toward either pole, the tides are alter- 
nately higher and lower at places having north or 
south latitude. One of the highest elevations, 
which is that under the moon, follows her toward 
the pole to which she is nearest, and the other 
declines toward the opposite pole; each elevation 
describing parallels as far distant from the equator, 
on opposite sides, as the moon declines from it to 
either side; and consequently the parallels described 
by those elevations of the water are twice as many 
degrees from one another as the moon is from the 
equator; then increase their distance as the moon 
increases her decHnation, till it is at the greatest. 



TroES 227 

when these parallels are, at a mean state, 47 degrees 
from one another; and on that day the tides are most 
unequal in their heights. As the moon returns 
toward the equator, the parallels described by the 
opposite elevations approach toward each other, 
until the moon comes to the equator, and then they 
coincide. As the moon declines toward the op- 
posite pole, at equal distances, each elevation de- 
scribes the same parallel in the other part of the 
lunar day which its opposite elevation described 
before. Whilst the moon has north declination, 
the great tides in the northern hemisphere are when 
she is above the horizon; and the reverse whilst her 
declination is south. 

" In open seas, the tides rise to very small heights 
in proportion to what they do in wide-mouthed 
rivers, opening in the direction of the stream of 
tide. In channels growing narrower gradually, 
the water is accumulated by the opposition of the 
contracting bank — like a gentle wind, little felt 
on an open plain, but stronger and brisk in a street; 
especially if the wider end of the street is next the 
plain, and in the way of the wind. 

*'The tides are so retarded in their passage through 
diflferent shoals and channels, and otherwise so 
variously affected by striking against capes and 



228 MECHANICS 

headlands, that in diflferent places they happen at 
all distances of the moon from the meridian, conse- 
quently at all hours of the lunar day. 

"There are no tides in lakes because they are 
generally so small that when the moon is vertical 
she attracts every part of them alike; and, there- 
fore, by rendering all the waters equally light, no 
part of them can be raised higher than another. 
The Mediterranean and Baltic Seas suffer very small 
elevations, because the inlets by which they communi- 
cate with the ocean are so narrow that they can- 
not, in so short a time, receive or discharge enough 
to raise or sink their surface sensibly. 

"Air being lighter than water and the surface 
of the atmosphere being nearer to the moon than 
the surf ace of the sea, it cannot be doubted that the 
moon raises much higher tides in the air than in 
the sea. Therefore many have wondered why the 
mercury does not sink in the barometer when the 
moon's action on the particles of air makes them 
lighter as she passes over the meridian. But we 
must consider, that as these particles are rendered 
lighter, a greater number of them are accumulated, 
until the deficiency of gravity is made up by the 
height of the column; and then there is an equi- 
librium, consequently an equal pressure upon the 



TroES n9 

mercury as before; so that it cannot be affected by 
the aerial tides. It is probable, however, that stars 
seen through an aerial tide of this kind will have 
their light more refracted than those which are seen 
through the common depth of the atmosphere; and 
this may account for the supposed refractions of 
the lunar atmosphere that have been sometimes 
observed. 

"You see now how the tides are caused; while 
there may be some influences at work other than 
those exerted by the sun and moon, the latter are 
the chief ones, so I will not attempt to explain any 
other. 

*'Here, on the Passaic River, we do not have 
excessive tides, as the highest on the coast near us 
seldom rise over ten or twelve feet. As a rule, tides 
rise highest and strongest in those places that are 
narrowest. In the Black Sea and the Mediterranean, 
the tides are scarcely perceptible, while at the 
mouth of the Indus, in the Bay of rundy,and other 
places, they rise thirty or more feet at times. The 
general rise, however, in mid-ocean, is from eleven 
to twelve feet. 

"The diameter of our moon is nearly 2,200 miles, 
and her distance from the earth is about 240,000 
miles; so you see it is not her size, but her prox- 



2S0 MECHANICS 

imity to the earth that gives her so much influence 
over the tides; for the sun, which is many times 
larger than the earth and moon combined, because 
of its being some ninety-three millions of miles away, 
exerts only one sixth of the attraction on the earth 
that the moon does. 

** These facts, children, should be remembered, as 
you may often be called upon to make use of them. 

*'0h, papa!" said Jessie "how many wonderful 
things there are in this world." 

"But I have not told you all, my dear. There is 
much more to learn, but I hope the knowledge you 
have now acquired will act as an incentive, and 
cause you to pursue this study further." 

Next morning Fred asked his father to enlighten 
himself and George regarding the making of a 
few simple meters, such as barometer, hygrometer, 
and a thermometer. He also wished to know if 
it would be possible for him to make a boomerang. 
Mr. Gregg told him he would be pleased to help 
him, and that there would be no difficulty in making 
a boomerang if he went to work at it earnestly. 

On the arrival of his father that evening, the 
subject was again introduced, and Mr. Gregg using 
the blackboard, laid out the following drawing 
and wrote the accompanyig instructions. 



H - 



TIDES ; 231 

"The best hygrometer of absorption is (according 
to Deschanel) that of De Saussure, consisting 
of a hair deprived of 

grease, which by its . mpb, - 

contractions moves 
a needle. When the 
hair relaxes, the needle 
is caused to move in 
the opposite direction 
by a weight which 
serves to keep the 
hair always tight as 
seen in the illustra- 
tion. Fig. 70. The 
hair contracts as the 
humidity increases. 
In the accompanying 
illustration A A and B 
B represent the frame; 
e f, the scale; a, screw 

for tightening the hair; J3 (b -S 

b, the hair; O, weight; 

H, thermometer. Fig. 70. Hygrometer 

"A neater hygrometer, and one on the same 
principle, may be made by taking an old tooth 
powder box (as deep a one as possible, since the 



U b 



/ 



232 MECHANICS 

longer the string, the more sensitive it is), and boring 
a hole through the centre of the top and bottom. 
Paste a kind of dial in paper on the top of the box; 
take a piece of catgut, or small fiddle string, and 
push it up through the hole in the bottom and 
out at the one in the lid. Glue the bottom end 
immovably, and let the top end move freely: make 
a small index of a strip of whalebone (Fig. 71); 
bore a hole in the centre, and fix it on the catgut 

with glue. Wet the catgut, see 
which way it turns, and mark 
Vet' and 'dry', accordingly on 
the dial. 

''So much for the hygrom- 
eter. Now 'about that curious 
thing, the boomerang. If the 
r^' r.. T ^ ,xy . f ollowlug dircctious are closely 

Fig. 71. Index of Hygrometer ° "^ 

adhered to, and the proper 
shape followed, a regular Australian boomerang 
will result. It is not difficult to make. Take a 
piece of hard wood, the natural shape of one of the 
segments of an ordinary wheel felloe, or bend in 
the wood; let it be 3^ inch thick, shaped as at Fig. 72, 
to be held in the right hand at A, which shows the 
way the edges of the side facing the left hand must 
be bevelled off. It requires a slight curve on the 





TIDES 233 

flat side; so that, if on a table, each end would turn 
about % inch. It is then a part of a very fine pitch 
screw, in motion similar to a piece of slate jerked into 
the air, the sole dif- 
ference being due to 
the slight curve in 

the back, which ^'^' '^^' Boomerang 

gives the screw motion, in conjunction with the 
forward and rotatory motion given by the hand. 
Sheet-iron would not do, as there would not 
be thickness to show the bevelled edge. The 
boomerang was made in the form of a cross, 
with four legs of equal length, bevelled, but it does 
not work as well as the regular form. You must be 
careful in throwing it as it may strike you on return." 
George asked his father to describe one and to 
explain its uses. Mr. Gregg told the boys that a 
boomerang, as used by the aborigines of Australia 
for a weapon or missile of war or in the chase, 
consisted of a flat piece of hard wood bent or curved 
in its own plane, and from 16 inches to 2 feet long. 
Generally, but not always, it is flatter on one side 
than on the other. In some cases the curve from 
end to end is nearly an arc of a circle; in others it 
is rather an obtuse angle than a curve, and in a 
few specimens there is a reverse curve toward each 



234 MECHANICS 

end. In the hand of a skilful thrower, the boomer- 
ang can be projected to a great distance, and made 
to ricochet almost at will. It can be thrown in a 
curved path, somewhat as a ball can be ''screwed" 
or "twisted," and it can be made to return to the 
thrower, striking the ground behind him. It is 
capable of inflicting serious wounds. 

*'It is very good of you, father," said Fred, "to 
tell and show us all these things; I'd like very much 
to have a very common, e very-day matter explained: 
the theory of the pump." The following questions 
also were asked by one or another on the same line: 
What is the greatest distance or height a pump of 
any type can be placed away from the water ? Is 
there any limit to the length of the delivery pipe to 
the tank.f^ What is the difference between a lift and a 
plunger or force pump.? Is it the sucker of the pump 
that draws the water up, or does it flow because the 
air being drawn out of the pump barrel and forced 
on the water outside, causes it to flow into the pump.? 

Mr. Gregg started in at once to give them the 
facts desired: "Theoretically, the greatest height a 
pump can be fixed above the water level depends 
on certain conditions: the atmospheric temperature, 
and the altitude the pump is to be fixed above the 
sea- water level. The higher the temperature, and 



TIDES 235 

the greater the altitude, the less distance the height 
of the pump can be above the water. The height 
to which water can be drawn from the source to 
the top of the bucket, or under side of a piston or 
plunger, when at the top of the stroke, or what is 
termed the 'height of suction,' cannot reach more 
than about 33 feet when the pump is at the sea level. 
If a tube about 34 feet long is immersed in a well, 
and the air is extracted by means of an air pump 
at the upper so that a vacuum is formed, the water 
will not rise in the tube until the air is expelled, 
when it will not rise more than 33 feet, even though 
there is a complete vacuum formed in the upper end 
of the tube. The reason why the watei" will not 
rise in the tube higher than this, is that the height 
of the water counterbalances the pressure of the 
atmosphere. This height is the theoretically greatest 
height that water will rise in a suction pipe. For the 
pump to discharge water, it is necessary for the water 
to be in motion, and to set and keep it in motion 
a portion of the water will rise, due to the atmos- 
pheric pressure. The shorter the suction pipe, 
the more certain the pump is of being completely 
filled at every stroke of the pump handle. 

"The action of the pump is as follows: The 
bucket on moving upward attracts the air, so that 



236 MECHANICS 

the atmospheric pressure on the surface of the 
water in the well causes the water to follow the 
bucket up the suction pipe, through the suction 
valve, into the working barrel. On the return 
stroke, the suction valve will close, the valve in the 
bucket will open, and the water which before was 
under the bucket will pass through it to the top 
side. When the bucket is again raised, the water 
will be lifted through the delivery valve into the 
delivery pipe. There is practically no limit to the 
height of lift, which may be any height consistent 
with the strength of the pump and the available 
power. The ordinary pump used for raising water 
to the level of the top of the bucket, is termed a 
lift pump; for raising water above this, a force 
pump or a plunger pump must be used, when the 
water is displaced by a solid plunger on its down- 
ward stroke, when the quantity of water raised 
will be equal to the volume of the plunger. This 
system may be repeated when water is to be lifted 
more than ordinary heights. ' 



X 

WALL MAKING AND PLUMBING 

A FEW evenings later, Mr. Gregg and his 
little family were gathered together on 
the river's bank, watching the movements 
of a number of pleasure boats and launches, when 
a good-sized tugboat came along and made quite 
a ''wash" as she steamed past the Gregg domain. 
Mr. Gregg noticed that this had actually carried 
down a portion of the bank near the new pier, and 
he called Fred's attention to it. The two, followed 
by George, walked to the pier, and, to their alarm, 
found that quite a piece of the bank had been carried 
away by the current, the tides, and the frequent 
wash of passing steamers. 

"This will never do," said Mr. Gregg. "We must 
protect the bank at this point, or the water will 
soon undermine and demolish our pier, for you see 
it is only near the landing where the bank shows 
signs of injury, and it is as badly damaged on one 
side as the other. This is caused by projection of 
the pier into the river, which prevents the water 

237 



238 MECHANICS 

from flowing in its regular course, and causes it 
to rush into the angle formed by the junction of 
the pier with the bank, thus cutting away the 
latter." 

*' Perhaps it will be best to build a sort of retaining 
wall against the bank for ten or twelve feet each side 
of the pier to prevent this rush of water from cutting 
away the earth. If we had field stones enough on 
the ground, it would be cheaper to use them, though 
they would not make as good a 'job' as either cut 
stones or concrete; since we haven't the stones, we'll 
build it of concrete, as you have some knowledge of 
that material, and I will engage Nick to help you." 

The next day Mr. Gregg ordered Portland cement 
and all the other materials required to build the 
wall, and engaged Nick, who promised to come the 
following morning. In the evening, Mr. Gregg 
had the boys in his den, and explained to them how 
to go about constructing the wall. He decided to 
have it built of concrete blocks about 1^ x 24 x 12 
inches, to be faced with good, strong, cement mortar 
on the face and ends, which would give the ex- 
posed wall a nice, smooth appearance. Mr. Gregg 
explained that there must be a foundation of stone 
under the concrete, formed by large bowlders or 
*' fielders," laid as closely together as possible. 



WALL MAKING AND PLUMBING 239 

the joints filled in with smaller stones and, when 
possible, cement mortar, to bind the whole into a 
solid mass — as shown by dotted lines in the illus- 
tration which he made on the blackboard. The 
blocks for the work were to be cast in wooden moulds 
or forms, which Fred and George could easily make 
out of boards taken from the dismantled bam. 




Fig. 72a. Retaining wall 

At the points where the wall was wanted, the bank 
was about 8 feet high from the bottom of the river, 



240 MECHANICS 

and it was determined to make the wall 8 feet high, 
2 feet wide at the top and 3 feet at the bottom, with 
the batter on the water side, the weight of the wall 
being 140 pounds per cubic foot. It is always best 
to have the inclined surface on the side of the wall 
where the water will be. The water at high tide 
rises to a level of 6 feet above the base C D. 

"In designing such a retaining wall," said the 
father, *'for water one side, and earth the other, or 
determining its stability, the principles generally 
followed may easily be worked out by Fred, or even 
by George. 

"Taking the earth side first, as shown in diagram 
Fig. 72 a, W C X, angle of repose of earth to be re- 
tained — 30 degrees; G C, the line of rupture; G C A, 
the wedge of earth at 112 pounds per cubic foot 
to be accounted for, the weight of which equals — 

^^I^X 112 lb.= *' '^"^ ^' X 112lb.==2,053 lb. 

"This will act at a point one-third the height of 
the wall H. From H erect a perpendicular H I 
equal to 2,053 lb. Set out the angle H I J equal 
to angle of repose, 30 degrees. From H erect 
a perpendicular to A C, cutting I J in J. Then 
J H equals the direction and magnitude of the weight 
of the earth acting on the wall. 



WALL MAKING AND PLUMBING 241 

"Produce J H through the wall toward the water 
side. Find centre of gravity of wall in K and the 
weight of the wall, which in this illustration equals — 
ABxCD^ ^g ^ ^^^^^ =^x|-Xl49 lb.=2,800 lb. 

''From where J H produced meets a vertical line 
drawn through the centre of gravity, K, in L set of 
L N equal to 2,800 lb.; make L M equal to J H; 
complete parallelogram L M O N, when L O equals 
resultant of earth and wall. 

"The magnitude and direction of P R can be 
found as in the first part of this article. Produce 
R P through the wall, and from where it cuts the 
resultant L O in S make S T equal R P. Let the 
diagonal L O now be produced so as to make S V 
equal to L O. Complete the parallelogram S T U 
V, when the resultant S U equals the combined 
resultant of earth, water, and wall, and as it passes 
within the middle third it can be considered safe. 

"Now, boys," said Mr. Gregg, "I have not only 
told you how to build a retaining wall, I have also 
told you how to make all the necessary calculations 
for designing it, as the same figuring and diagraming, 
on this principle, will answer for any sea wall re- 
quiring like conditions. 

"I know you both understand figures and gee- 



242 MECHANICS 

metry enough to make such calculations, if you 
are ever called upon to do so." 

The next morning, before the boys had finished 
their breakfast, Nick was on hand ready to go to 
work, equipped with a pair of hip rubber boots 
which would enable him to wade in water two feet 
deep and remain dry. 

Fred and George were soon ready and Mr. Gregg 
went out to tell them the proper way to commence. 
The foundation was the first consideration, so an 
examination of the site and was made, the length of 
the proposed walls measured off. While waiting for 
the tide to ebb to its lowest point, Nick and the 
boys busied themselves gathering up stones for the 
foundation and wheeling them to the point nearest 
where they were to be used. 

After gathering all the stones thought necessary, 
the question of making the moulds for the concrete 
blocks was considered, and, as the greatest bulk 
of the blocks would be simply blocks with square 
ends and square faces, the moulds for these would be 
a box having inside dimensions of 12 inches deep, 
12 inches wide, and 24 inches long. These dimensions 
would then allow of blocks being made in the 
moulds that will contain exactly 2 cubic feet. The 
mixed concrete was dropped gently in the mould 



WALL MAKING AND PLUMBING 243 

and lightly tamped so as to make it solid. The 
mixture consisted of not less than 3 of cement, 5 
of sand, and 7 of very fine gravel or broken stone, 
no piece being larger than a white bean. It was 
mixed in the same manner and in accordance with 
the rules given for making concrete for the sidewalk 
in Chapter I. 

The mould should rest on a smooth block of stone, 
wood, or other suitable material, while being filled 
and tamped, and when full the surplus should be 
levelled off, by a straight-edge — wood or iron — 
drawn over the top of the mould, until all the sur- 
plus is removed. The mould is then allowed to 
stand a little while until the concrete ''sets" fairly 
hard, when the mould may be removed. To make 
it easy to take the block out of the mould, the 
inside should be well sprinkled with neat cement 
before the concrete is put in, and the box itself 
might be made slightly tapering to permit the block 
to move out easy. This method, however, is not 
to be recommended, as the blocks do not fit so well 
in a wall as when left perfectly square. There are 
a number of devices for making moulds so that 
delivery of blocks may be easy. One of the best 
is to hinge one corner of the mould with heavy hinges, 
while the opposite diagonal corner is left loose but 



244 MECHANICS 

held in place by a strong hasp and staple. When the 
box or mould is full and the block ready to remove, 
the hasp is loosened, the mould opens across at the 
two corners and frees the block. Should there be 
any holes or defects on the face of the blocks, they 
can be filled with cement mortar made with 2 of 
cement and 3 of clean sand. Blocks of this size 
should season not less than 4 or 5 days, to set hard 
before being used. 

A portion of these blocks must have a bevel face 
on them to form the batter on the front of the wall. 
There must also be a proper proportion of them 
having their ends bevelled to the batter of the 
wall, to use as "headers." A header in brick, stone, 
or concrete, is a unit, or piece, that is laid in the 
wall with its ends showing through on the face, 
while a ''stretcher" shows its whole length on the 
face of the wall. Other portions of brick or stone, 
when built in a wall, are called ''closers." 

The batter on the blocks is formed by making 
one side of the mould lower than the other. In 
this case, the diflFerence in the width of the sides 
of the mould would be 13^ inches; because the height 
of the wall being 8 feet, the blocks 1 foot thick, and 
the batter 1 foot, there would be a falling off on 
each block of 13^ inches in order to have the top 



WALL MAKING AND PLUMBING 245 

front of the wall 12 inches back from the bottom 
front. The ends of the header blocks may be bat- 
tered by placing in the ends of the mould a piece 
of wood 12 inches wide, and the lower edge IJ^ inches 
thick, and the top edge planed to a thin wire edge. 
The end or section of the plank will then have the 
appearance of a wedge 12 inches long, Ij^ inches 
thick on one end, and tapered to nothing at the other 
end. When the block is taken from the mould, and 
the wedge piece removed, the block will show the 
same batter on its end as the stretchers do on their 
face, and they can be built in together without 
showing any diflFerence in the slope, if the work is 
carefully done. 

Nick, who had had some experience in this kind 
of work, found no difficulty in understanding the 
whole process. 

At low tide he set to work to make a solid bed 
for the foundation, while the boys handed him the 
stone and the prepared mortar as he required it, 
so that before the tide rose one side of the stone 
foundation was ready to receive the concrete blocks. 
During the interim between tides, Nick and the 
boys made the moulds, prepared for mixing the 
concrete, and got old timbers and lumber for a 
temporary scaflFolding. After the moulds were made 



246 MECHANICS 

and some concrete mixed, Nick began on the blocks. 
It was not long before he had a sample, which seemed 
all right, and before he stopped quite a number of 
them were ranged on boards "setting." 

On the sixth day after it had been commenced, 
the job was entirely finished. The joints in the wall 
had been nicely "pointed" up with cement mortar 
by aid of a fine-pointed trowel. The back, or ground 
side of the wall was filled in with earth, and danger 
to the pier was entirely removed. 

That night Mr. Gregg told the boys and Jessie — 
who had watched closely the growth of the wall — 
quite a lot about Portland cement and concrete, 
which interested them very much. Portland cement 
as we have it now was unknown a hundred years 
ago, but an Englishman invented the method of 
making it and properly proportioning the various 
materials used. Fifty years ago there was scarcely 
any made in this country, the little that was used 
being imported from England, and later from Bel- 
gium; but now more of it is made and used in the 
United States than anywhere else in the world. 
He pointed out that the building of the Panama 
Canal was made much easier and less costly because 
of cement, and that the largest dam ever built had 
just been suggested, to dam the Mississippi near 



WALL MAKING AND PLUMBING 247 

Keokuk, Iowa. This would be over 5,800 feet 
long and nearly 40 feet high and from 25 to 35 feet 
thick. He told of the various big storage dams 
being built and comtemplated by the United States, 
in Montana, Arkansas, Nebraska, Wyoming, New 
Mexico, Dakota, Texas, and many other places, at 
a cost of hundreds of millions of dollars — which 
never would have been attempted if concrete had 
not been available. He also made mention of the 
great wall that now protects Galveston from the 
ravages of the sea. It is not many years since 
Galveston was almost destroyed by tidal waves 
that caused an enormous loss of life, and destruction 
of property amounting to over $17,000,000. The 
wall was built to prevent a recurrence of similar 
disasters. It is 17,503 feet long, 17 feet high, and 
16 feet thick at the base. Another recent work 
is the enormous dam built by English engineers 
across the river Nile at Assiout, about 250 miles 
above Cairo in Egypt, which increases the area 
of good land some 300,000 acres. Ancient Babylon 
is again to blossom and become a beautiful country 
to live in, for British engineers are laying out plans 
for building storage dams and irrigating canals 
in these now sandy and barren lands. All, or nearly 
all, of these works and proposed works would never 



248 MECHANICS 

have been thought of, if Portland cement had not 
been in existence. 

Mr. Gregg, after finishing his talk on concrete, 
noticed that George had two fingers on his right 
hand tied up, and on inquiry was told that George 
had his fingers hurt by a concrete block falling on 
them just as the retaining wall was being finished. 
The father insisted on seeing the bruised fingers and 
found they were not badly hurt, though the skin in 
one place was broken. George explained that his 
mother had washed his hand, dressed the wound, 
and applied an antiseptic to it, so that it was all 
right now and did not pain him. 

"You were wise to go to your mother and have 
your bruise attended to immediately, otherwise 
you might have had something serious happen to 
you, as lockjaw frequently comes from wounds of 
that kind, if deep enough and not attended to im- 
mediately. It is often said that lockjaw or tetanus 
is caused by a wound made by a rusty nail. It 
is certainly bad to be wounded with a rusty nail — 
or any other rusty iron — and tetanus may follow; 
but it does not follow because the nail is rusty, but 
because the tetanus microbe that may be on the 
nail, or on the skin when the wound is made, is 
carried into a favourable place for development. 



WALL MAKING AND PLUMBING 249 

**This tetanus microbe, which has a long name, 
is very plentiful and is scattered broadcast by every 
gust of wind. It is a microbe of dirt, and the 
ground and street abound with it. Its first home and 
breeding place is in the intestines of horses and other 
domestic animals, but its greatest danger to the 
human family is when it gets into the blood by way 
of a wound. Cleanliness, in this as in many other 
cases, is both a preventive and a cure." 

"Father," said Jessie, "I saw a very funny thing 
to-day while watching Nick and the boys finish 
the wall. The train across the river came to a 
standstill for some reason or other, and, as I was 
watching it, I saw three puffs of steam go out of 
its boiler, and a short time after I heard three loud 
whistles. This seemed to me quite curious, but 
while I was thinking over it, there were three more 
jets of steam, followed by three .more 'toots.' How 
was it that I saw the toots before I heard them.''" 

"This is a question, my dear, that will require 
some little time and thought to answer properly. 
In the first place, you must understand that light 
travels very much faster than sound and that sounds 
do not reach you until some time has elapsed, if 
you are a little distance away. You see a flash of 
lightning, and a little while after you hear the 



250 MECHANICS 

thunder; and if you count 1, 2, 3, in the ordinary 
way, between seeing the flash and hearing the 
thunder, you may be fairly satisfied the source of 
the thunder is well on to three miles away. This, of 
course, is not exactly correct, but approximately 
so. Every time you count one, it stands for a mile. 
According to science, light travels 186,000 miles a 
second, while sound only travels at the rate of 
1,090 feet per second at a temperature of 32 degrees 
Fahrenheit, or freezing, its velocity being increased 
at the rate of one and one tenth feet per second for 
every degree above this temperature. So you see 
light travels nearly a million times faster than, sound, 
and this accounts for your seeing the puflfs quite 
a little while before you heard the 'toots', as you 
call them. There are many curious and inter- 
esting things about light and sound which I'd like 
to describe to you sometime. 

"Sound travels in dry air at 32 degrees, 1,090 feet 
per second, or about 170 miles per hour; in water, 
4,900 feet per second; in iron, 17,500 feet; in copper, 
10,378 feet; and in wood, from 12,000 to 16,000 feet 
per second. In water, a bell heard at 45,000 feet, 
could be heard in the air out of the water but 656 
feet. In a balloon, the barking of dogs can be 
heard on the ground at an elevation of four miles. 



WALL MAKING AND PLUMBING 251 

Divers on the wreck of the Hussar frigate, 100 feet 
under the water, at Hell Gate, near New York, 
heard the paddle wheel of distant steamers hours 
before they hove in sight. The report of a rifle 
on a still day may be heard at 5,300 yards; a mil- 
itary band at 5,200 yards. The fire of the English, 
on landing in Egypt, was distinctly heard 130 miles. 
Dr. Jamieson says he heard, during calm weather, 
every word of a sermon at a distance of two miles. 
The length of the sound waves in the air is some- 
times many feet, while the length of the longest 
light wave is not more than .0000266 of an inch, 
it is no longer a mystery why we can hear, but can- 
not see, around a corner." 

The children were greatly interested by these 
familiar marvels and made their father promise 
that he would resume the talk some other evening 
and tell them about thermometers and barometers. 

The late afternoon next day was taken up with 
an excursion on the Caroline down the river to 
Newark, where Fred induced his father to purchase 
a full soldering outfit, as the boys wanted to try 
some plumbing and soldering work. There had 
been a plumber at the Gregg home nearly all that 
day doing repair work of various kinds, and Fred, 
who had watched the workman, concluded he could 



252 MECHANICS 

have made the repairs himself if he had had the 
proper tools. 

An hour or two in the city, then a pleasant sail 
home, proved a fine ending for a day's labour. 

The next day, after school, George and Jessie 
assisted their mother "making garden," planting 
flowers, trimming bushes, and destroying weeds, 
while Fred gave the Caroline another coat of 
varnish, and finished painting his little workshop, 
which now looked very snug and tidy. He soldered 
up all the leaks in every kitchen utensil he found 
defective, much to the delight of his mother and 
the maid. Fred found many things about the 
house wanting more or less attention, so he deter- 
mined to try to put them in order. He discovered 
that to make a good job of soldering, he must 
first make the metal to be fastened together, per- 
fectly clean and free from rust, dirt, or grease, 
the parts around the leak being scraped bright and 
smooth. He found some little difficulty in getting 
the solder to the exact place he wanted. In the 
outfit his father bought him, was not only a solder- 
ing iron, — which is not iron but copper — but a 
scraper, a lump of solder, a box of rosin, a piece of 
chamois leather, a bottle of muriatic acid, and a 
piece of sal-ammoniac, to be crushed fine and 



WALL MAKING AND PLUMBING 253 

dusted over any surface that is to be finished bright. 
Fred had no trouble in soldering holes of small 
size in teakettles, tins, or such things as he could 
handle easily, for the impaired portions could be 
placed in a horizontal position before him and the 
solder applied readily. A leak in an upright water 
pipe in the shed, however, gave him a hard time, 
for he could not get the solder either to run up hill 
or to stay on the place where it was put. He got 
over this difficulty, however, by making a clay 
dam, a "tinker's dam" — mixing clay until it was 
soft, then winding a strip of it around the pipe 
just below the leak and applying the solder until 
the hole or crack was entirely covered, when a 
good solid job resulted. Of course, before applying 
any solder, all the water was drained from the pipe, 
and the defective part was thoroughly scraped. 
When the work was done, there was an edge of 
solder left projecting from the pipe, which Fred 
rasped away with a course rasp, leaving just enough 
solder to cover the leak properly. He then sand- 
papered the work and it looked almost as "good as 



new. " 



It is easy enough to solder across the work when 
level, even if the article being soldered is round, 
because the metal can be worked across the top 



254 MECHANICS 

and down the sides; but on the under side, it may be 
necessary to make use of a clay dam. A plumber's 
work covers a lot of things, among which may be 
mentioned metal roofing, wall flashings, water- 
pipes of all kinds, drain connections, hot water 
and steam fittings, hot-air and ventilation fittings, 
stove and range settings, and many other things 
connected in some way or another with the fore- 
going. Many times an offensive odour is notice- 
able in the cellar, or near the line of drainage, and 
it is often difficult to locate the source, so that 
expensive excavations are made before the trouble 
is remedied. Plumbers and drainage men often 
use what is termed '*the peppermint test," to 
find where the leakage exists, and this is partic- 
ularly suitable for the examination of existing soil 
pipes and drainage fittings. This test consists in 
pouring a small quantity of oil of peppermint or other 
substance possessing a pungent, penetrating, and dis- 
tinctive odour, into the pipe or drain. The defective 
pipe or joint is then located by the escaping odour. 
It is very important that defects of this kind 
should be located and repaired immediately, for 
odours emanating from drains or soil pipes carry 
with them germs of the kind most dangerous to 
human health and life. 



WALL MAKING AND PLUMBING ^55 

Some taps in the bath room and over the kitchen 
sink were not working freely, and others were "drop- 
ping" a httle. Fred, after cutting off the water 
from the main, unscrewed these and put new rub- 
ber washers in some, wound cotton twine around 
the plugs of others, and made the tight ones work 
easy by removing worn out washers and cut strings. 
He also fixed the hydrants on the lawn in the same 
manner, and made all the taps in and about the 
house work tightly and smoothly. 

When Mr. Gregg arrived home, Fred told him 
all he had done, showing the tin pans and the 
leaky pipe he had soldered, and he straightened up 
with pride at being told that he was already "quite 
a plumber." 

After tea, the family went down to the river's 
bank and chatted awhile on home matters; then 
shortly after the sun went down, they adjourned 
to "the lion's den." 

"Now," said George, ''father will tell us about 
barometers and thermometers, as he promised." 

"Well," said Mr. Gregg, "I'm pleased to know 
you are so ready to listen to my talks, and I hope 
you'll remember some of the facts I've been telling 
you. 

"There are many kinds of barometers, but all 



256 MECHANICS 

are constructed about on the same principle, and 
on the old theory that 'nature abhors a vacuum'. 
There may have been some kind of an instrument 
that did service as a barometor in the early ages, 
but we have no knowledge of it. The instrument 
as we now know it had its beginning with Galileo, 
Torricelli, and Pascal, but was not perfected until 
about 1650. Good barometers require the greatest 
possible care in their construction, and there ought 
to be two or more standing together as checks on 
one another in order to obtain correct results. 
The mercury used must be pure and good, free 
from all other substances and from air bubbles or 
films of air on the sides of the 
bulb. Simple barometers, suit- 
able for ordinary purposes, can 
be easily made. I will describe 
one, and make a sketch of it 
on the blackboard. 

"This simply consists of a 
wide-mouthed glass bottle filled 
with ordinary drinking water up 
to the point indicated by the 

Fig. 73. Simple barometer I^l-t^j, ^ (FJg^ 73). Jq this Is 

dipped an inverted glass flask, or an incandescent 
light bulb, the extremity of the neck being al- 




WALL MAKING AND PLUMBING 257 

lowed to dip just below the surface of the 
water. 

"The flask should be inverted quite empty 
during wet weather, and as long as the atmosphere 
remains in a stormy condition, no change in the 
water takes place; but immediately the weather 
becomes finer, the water will rise in the neck of the 
inverted flask, and, if a continuance of fine weather 
be probable, will rise to the point indicated by 
letter B. 

"I have found this simple contrivance to give 
sure and early warning of the approach of rain, 
and I need hardly remark that the principle upon 
which this little weather glass acts is exactly sim- 
ilar to that of the ordinary mercury barometer, 
for the rise and fall of the water is due to the respec- 
tive increase or decrease of atmospheric pressure. 

"By dividing the neck A B into six or eight di- 
visions, with the aid of a diamond or piece of flint, 
and then marking the lines so cut, with ink, an 
approximate graduation of degrees of pressure 
may easily be obtained. 

"I show you a water barometer here, (Fig. 74) 
that IS somewhat less hard to construct than the 
one I have already described, as the parts are easier 
to obtain. 



258 



MECHANICS 




**It consists of a bottle, containing water, inverted 
and suspended with its mouth in the jar of the same 
fluid. It is capable of roughly indicating atmos- 
pheric changes in a similar way to 
the mercurial barometer. When the 
atmosphere becomes denser, the great- 
er pressure on the surface of the 
water in the jar causes it to rise in 
the bottle; while with a lesser density 
it falls. As with the mercurial barome- 
ter, temperature makes a slight 
difference, which, strictly speaking, 
should be allowed for; but, as the ar- 
rangement is of such a simple character, 
this may be ignored. Water, also, is more subject 
to evaporation than mercury, besides going stag- 
nant, and will require occasional changing and 
replenishing. 

"A barometer of a more scientific character, 
and more presentable, is, I think, within your range 
of skill, and it may be made as follows: Obtain a 
glass tube, closed at one end, about two feet ten 
inches long and three eighths of an inch thick, with 
a bore of about three sixteenth inch. A circular 
turned wood box, one and one half inches in diameter 
and one and one fourth inches deep, is required for 



Fig. 74. 
Barometer 



WALL MAKING AND PLUMBING 



259 



the cistern. Cut out the bottom and glue on in- 
stead a piece of leather, sagging loosely. Then 
cut the lid in two, and make an opening in the 
centre to receive the tube. 

"The mahogany base, shown in two halves by 
A and B (Fig. 75), is 3 feet 1 inch long, 3^ inches 
at its greatest width, 2 inches at its least width, 
and ^ inch thick. Make a groove down the 
centre to admit the tube, and cut an opening 2 
inches square right through the wood at the round 
end. Glue at the back 



of this a circular piece 
of pine or cedar, 3 inches 
in diameter and J^ inch 
thick, and screw a semi- 
circular piece of the 
same thickness at the 
other end, with a ring 
for hanging. 

"Fill the tube by de- 
grees with pure mercury, 
boiling each portion, as 
introduced, by holding ^^' '^'' "^^^^^^^^ 

the tube in a nearly horizontal position over a spirit 
lamp, taking care not to crack it by too sudden 
heating. Half fill the wooden cistern with mercury. 




260 MECHANICS 

and when the tube is full, place a finger over the 
end, carefully raise it to a vertical position, and 
lower the open end below the surface of the mercury 
in the cistern. While some one holds the tube, 
glue on the two halves of the box lid and seal up 
the opening round the tube with wax or cement. 
Then fasten the tube to the base with brass cUps 
and screws, and secure the cistern from shifting 
by gluing in wedges of wood. A thumb screw, 
with washer, for regulating the height of the 
mercury, is fixed at the bottom; this presses 
on a cork washer glued to the leather of the 
cistern. 

"A hollowed hardwood boss is screwed over the 
top end of the tube, and a hollowed circular turned 
boss of mahogany, C, is glued over the bottom. The 
ivory or cardboard scale D, is of inches and tenths, 
from twenty-six and one half inches to thirty-one 
inches, the distance being measured approxi- 
mately from the surface of the mercury in 
the cistern. A vernier having a scale of eleven- 
tenths of an inch, divided into ten parts, works in 
a slot on the scale and should be attached as shown 
atD. 

** Before screwing on the scale, fix its correct 
position by comparison with the standard barometer. 



WALL MAKING AND PLUMBING 261 

It is usual to place a small thermometer on the 
other side. 

**With regard to the thermometers, it would be 
quite out of place here to discuss them at length, 
or to oflFer you a scientific explanation of the prin- 
ciples governing their construction. I may say 
however, that, as the barometer is intended to meas- 
ure the diflFerent degrees of density of the atmos- 
phere, so the thermometer is designed to mark the 
changes in its temperature, with regard to heat and 
cold. The first thermometers, so far as we know, 
were made less than three hundred years ago, and 
water, spirits of wine, or alcohol, and oil were used 
to fill the bulbs, in the order given. It was the 
great Halley, of 'Halley's Comet' fame, who first 
made use of mercury or quicksilver in these instru- 
ments, because of its being highly susceptible to 
expansion and contraction, and capable of showing 
a more extensive scale of heat. It is owing to this 
quality of expansion and contraction that the de- 
grees of heat and cold can be measured. If you put 
your thumb on the bulb, you will notice the quick- 
silver in the little tube gradually rise until it reaches 
the limit of the thumb's heat. Thermometers, in 
this and nearly all English-speaking countries, 
make use of the Fahrenheit scale, which is diflFerent 



^6^ MECHANICS 

from those used in some other places; and this often 
causes trouble and annoyance. 

*'The scale of Reamur prevails in Germany. He 
divides the space between the freezing and boiling 
points into 80 degrees. France uses that of Cel- 
sius, who graduated his scale on the decimal system. 
The most peculiar scale of all, however, is that of 
Fahrenheit, the renowned German physicist, who, 
in 1714 or 1715, composed his scale, having ascer- 
tained that water could be cooled under the freez- 
ing point without congealing. He, therefore, did 
not take the congealing point of water, which is 
uncertain, but composed a mixture of equal parts 
of snow and sal-ammoniac, about fourteen degrees R. 
This scale is preferable to both those of Reamur 
and Celsius, or, as it is called, Centigrade, because: 
(1) The regular temperature of the moderate zone 
moves within its two zeros and can, therefore, be 
written without + or — . (2) The scale is divided 
so finely that it is not necessary to use fractions 
whenever careful observations are to be made. 
These advantages, although questioned by some, 
have been considered so weighty that both Great 
Britain and America have retained this scale, while 
nations on the Continent of Europe use the other 
two. The conversion of any one of these scales 



WALL MAKING AND PLUMBING 26S 

into another is very simple. (1) To change a 
Fahrenheit temperature into the same given by 
the Centigrade scale, subtract 32 degrees from 
Fahrenheit's degrees and multiply the remainder 
by %. The product will be the temperature in 
Centigrade degree. (2) To change from Fahren- 
heit to Reamur's scale, subtract 32 degrees from 
Fahrenheit's degrees and multiply the remainder 
by %. The product will be the temperature in 
Reamur's degrees. (3) To change a temperature 
given by the Centigrade scale into the same given 
by Fahrenheit, multiply the Centigrade degrees 
by % and add 32 degrees to the product. The 
sum will be the temperature by Fahrenheit's scale. 
(4) To change from Reamur's to Fahrenheit's 
scale, multiply the degree on Reamur's scale by 
% and add '32 degrees to the product. The sum 
will be the temperature by Fahrenheit's scale. A 
handy table can easily be figured out from the data 
given." ' 

Mr. Gregg concluded his conversation for the 
night at this point, but promised to take it up again 
the first available evening. 

Two or three nighiis afterward it was very wet 
and dreary. The boys and Jessie were called into 
the den by Mr. Gregg, where a brisk fire, made of 



264 MECHANICS 

limbs and branches gathered by the boys, was 
burning in the little fireplace, and the room looked 
bright and cheerful. The young folks all drew up 
around the fire to listen. 

"I have so many things to talk to you about," 
said he, "'that I scarcely know where to begin; 
however, I promised to tell you something con- 
cerning springs, so I will make these useful contriv- 
ances my theme to-night." 

"There are many kinds of springs, but I will 
only talk of steel or other metal springs; and even 
then must limit myself to a few. The carriage or 
laminated spring is probably the most in use, as 
it is an important factor in the construction of all 
classes of railway trucks and carriages, locomo- 
tives, automobiles, road carriages and light wagons 
of all kinds. These are also much used in the manu- 
facture of invalids' chairs, children's perambula- 
tors, and many other things. The springs used 
in the construction of the largest locomotives are 
big afifairs and often weigh over 500 pounds. These 
are bearing springs and carry the whole weight of 
engine and boiler. There are, of course, a number 
of these springs to each engine. Springs on the 
coaches and carriages are somewhat lighter and 
more flexible than those on the heavier trucks. 



WALL MAKING AND PLUMBING 265 

The double spring, shown at Fig. 76, is known 
in railroad parlance as a 'draw-spring.' One of 
these is secured at each end of the car, and used 
to attach or couple the cars together, or to attach 
the engine to the train, the object being to lessen 
the bump or impact of the blow when the engine and 
cars come together. The eflfect is the same when 
the engine starts a train; 

the springs in the first f" '-5i/t ---♦. 

car draw out, then the ' 
springs on the second 
car do likewise, and 
this causes the load of 
the whole train to fall 
on the engine gradual- 
ly, a matter of great 
importance in railway 
economy. If it were not 
for bearing springs on the trucks and carriages, 
it would be almost impossible to use railroads for 
passenger traffic or for carrying fine goods, as 
the jolting and pounding on the iron rails 
would shake things to pieces, destroy the carriages, 
and pound the roadbed and bridges to bits in a 
very short time. Now, by the aid of steel springs, 
you ride in a Pullman as smoothly almost as 




91^9 Leaves per ^prtn^ ^ 

Fig. 76. Car-spring 



266 MECHANICS 

in a boat, so you see how useful springs are to 
mankind. 

** There are many kinds of bearing springs, but all 
are built in the same manner, of steel leaves, made 
of different dimensions to suit conditions. As 
you will see in the diagram, the sheets of steel are 
laid over each other, like the scales of a fish, and 
made shorter as they approach the top. All the 
leaves are fastened together by having an iron 
buckle driven onto the middle, as shown, while 
hot, and when this cools, it shrinks and clasps the 
whole so tight it cannot be taken off until heated 
or cut. I could tell you of many other kinds of 
springs — watch springs, gun springs, trap springs, 
spiral springs — used for various purposes, but I 
will end this subject by describing to you something 
you can make for yourself, if you wish; namely, 
a cross-bow, which is very simple. I make on 
the blackboard a diagram, (Fig. 77), with A repre- 
senting the stock, 5 feet long; B, the bender, 6 
feet long, which should be made in four pieces. 
The front piece should be % inch thick, the 
three inner pieces J^ inch thick. . C are brass 
ferrules to keep the leaves of the bender from 
shifting; D the string, which should be very strong. 
The bender should be cut out of straight well- 



WALL MAKING AND PLUMBING 267 

seasoned ash, rock elm, or hickory. Instead of 
brass ferrules, strong brass or copper wire can 

be used, properly 
twisted at the 
joints. 

"The gyroscope 
has become quite 
famous of late, be- 
cause of its having 
been employed as 
a steadier for the 
monorail car, and 
proposed as a regu- 

Fig.77. Cross-bow spring j^^^^ ^^ gOVCrnor 

for aeroplanes, so that I think it will not be 
amiss to tell you that a study of this toy is well 
worth any time and labour you may spend on 
it. There are great possibilities within this 
little instrument and its applications. I do not 
intend dealing with its principles, or with rotation 
problems generally, as they would, I fear, be beyond 
your present comprehension, but I will confine my- 
self to describing the toy and showing you how it 
can be made, though it would be much cheaper to 
buy one from a dealer. The instrument consists 
of a ring of brass or other metal, like a curtain ring. 




268 MECHANICS 

and a smaller brass ring attached to a thick disc 
of white metal, or a metal disc with a thickened 
rim, as shown in Fig. 78. This disc is securely 
fixed to a metal pin, which is passed through two 
holes in the outer brass ring, and 
at one side a small rounded nut 
or ball of brass is screwed on the 
f^^^^^^l^ outer ring. The metal disc is at 
right angles to the outer ring. 
g. . yroscope j^ ^ ^^^^ .^ wound scvcral times 

round the metal pin, the outer ring held in the left 
hand, the pin and metal disc will revolve at a very 
high speed, while the outer ring remains stationary. 
The gyroscope can be placed on the knob, and while 
the disc is revolving the outer ring can be placed 
at any angle, and will remain stationary. It is 
also possible to balance it at any angle on the top 
of a support, such as the tip of a stick." 




PART II 
EVERYDAY MACHINES 



SOME PRACTICAL ADVICE 

SOME of our inventions and some of our dis- 
coveries are of comparatively recent date, 
but most of them had their beginnings cen- 
turies before historical times, as many of our greatest 
inventions are the result of gradual growth and de- 
velopment. The early discovery, by some unknown 
persons or persons, of the making of bronze and the 
hardening of it, led up to stone and woodcutting, 
perhaps to the breaking-up and smelting of iron 
ore, and the extraction of the metals. This again 
opened the way for the making of steel, a dis- 
covery that placed in the hands of man a source 
of power which enabled him to overcome many 
natural diflSculties. One improvement led the way 
to another, and made other improvements possible. 
Take locomotives and steamboats for instance. 
The making of a raft, no doubt, suggested the canoe, 
and this led to the built-up boat, and the ship. 
The paddle and the oar doubtless led up to the side- 

271 



272 MECHANICS 

wheeler, and the scull to the propeller. The 
crude steam engine of Hero very likely suggested 
the steam engines now in use, and this new power 
rendered it easy for Stephenson and Fulton to 
perform their work; but, if either of these inventors 
were to come back to the earth and examine 
the great steamers of to-day, or the perfect 
and powerful locomotives now in use, they would 
be surprised to think that the present tract- 
able monsters, were the outgrowth of their early 
efiforts. 

In the same manner may be traced the same gradual 
growth in all the arts and sciences; for step by step, in 
every department of life, have completeness and per- 
fection come to us. It is not yet one hundred years 
since Congreve invented or rather completed the 
invention of the *' Parlor match," called in his 
day, the "Lucifer match." This grand achieve- 
ment was accomplished after many failures in 
the efforts of chemists for ages. The perfection of 
the match was a great blessing to humanity, as the 
old methods of making a light or fire were tiresome 
and very uncertain. So it is with many of the bless- 
ings we enjoy to-day: they are simply the results 
of the struggles of many unknown minds, the threads 
of which were gathered up and pieced together by 



SOME PRACTICAL ADVICE 273 

one master mind, so as to be made useful and profit- 
able to mankind. 

In the early and middle ages, the inventor was 
looked upon as a wizard, a sort of inferior demon, 
or, at best, an uncanny kind of man, and a proper 
subject for the stake. When, by superior wisdom 
and skill, he invented some machine or device, or 
discovered some new and better method of accom- 
plishing a useful end, he was at once looked upon as 
a necromancer in league with his Satanic majesty, 
and, therefore, unfit to associate with or be recog- 
nized as a Christian. History records many in- 
stances of inventors and progressive men being 
persecuted — and executed — because of their hav- 
ing discovered or invented something which would 
interfere with some vested or imaginary rights. 
The new inventions must be destroyed or put 
away out of sight and hearing, and the most power- 
ful influences were employed to bring about this result. 
The stories told of Friar Bacon, Papin,Crompton, and 
hundreds of other inventors, give us a few of the 
reasons why so little progress was made in the arts 
and sciences previous to the sixteenth century. 

Down to a period within the past few years the 
term invention has been considered almost synony- 
mous with the word chance. An inventor, was a 



274 MECHANICS 

lucky individual, who had happened to hit 
upon some new idea, not so much by his own great 
ability as by good fortune, similar to that which 
brings success to the purchaser of a lottery ticket. 

In many cases this was really the true state of 
affairs. Men who experimented in various me- 
chanical pursuits often stumbled upon results, 
which they perceived to be useful and valuable, 
and, if they protected the invention by patent, 
they often became wealthy. 

At the present time this meaning of the word 
invention must be greatly modified, if not altogether 
abandoned. The law which controls the action 
of the forces of nature is becoming so well under- 
stood among all classes of mechanics that chance 
invention, in the early sense of the term, has almost 
become an impossibility. Success can be assured 
only to the man who has tried to win it by the 
acquirement of the necessary knowledge, to be ob- 
tained by steady application and hard study. In 
the pursuit of discovery, the old saying, "knowledge 
is power," never has had more force than when 
applied to unravelling the tangled web of nature's 
mysteries. ''Science," says Lord Brougham, "is 
knowledge reduced to a system." 

A man may have a lifetime of practical ex- 



SOME PRACTICAL ADVICE 275 

perience and amass a fund of knowledge of great 
use to himself, but entirely unavailable for others. 
But if his experience be combined with that of other 
men and systematized into a regular order, it 
becomes part of the science of that branch of in- 
dustry, and although the person himself may have 
a profound contempt for science and theory his 
work may be quite scientific. 

Ignorance, in the past centuries, was another 
great factor in preventing mechanical progress. 
New machines and labour-saving devices were looked 
upon by the great mass of workers as contrivances 
designed to deprive them of the means of making 
an honest livelihood, and this point of view caused 
the people to smash and burn many machines that 
had cost great labour and expense to the unfortunate 
inventor. But, as public schools became more 
numerous and learning increased, the way of the 
inventor became smoother. The more enlightened 
nations encouraged inventors and inventions, and 
now our country has on its statute books laws for 
this purpose, the most liberal in the world. 

The opportunities for obtaining mechanical and 
scientific knowledge and technical instruction are 
now so many and so easy of access that inventors 
have but little trouble in acquiring the data and 



276 MECHANICS 

facts essential to their purposes. The eariiest 
students had nothing but their own observations 
and experiences to build on, and even as late as 
the eighteenth century, men had to grope in the 
dark for the data required to carry out their 
ideas. A brief examination of the early trea- 
tises on mechanics and the rude illustrations 
in the works of Leopold, Amoutons, and Desa- 
guliers will reveal the germs of many modern 
machines. 

The inventor of to-day, however, must proceed 
by a different path from his predecessor, if he ex- 
pects to succeed in the present advanced state of 
mechanical arts. The demonstration of the me- 
chanical equivalent of heat, the discovery of the 
correlation of the physical forces, and the develop- 
ment of the sciences of thermo-dynamics have fur- 
nished powerful weapons for the advancement of 
mechanical science, and he who does not use them 
is at a woeful disadvantage in the fight. There 
is no "royal road" to success for the inventor, and 
I hope you will always bear this in mind when at- 
tending to your studies, for you must remember 
that it is nearly always necessary to use formulae 
and symbols to express relations, which are hardly 
within the range of words, and often a combination 



SOME PRACTICAL ADVICE 277 

of data obtained from different sources may be 
used to derive entirely new relations. 

It is here that invention, in the modern sense of the 
term, comes in to hold a place midway between theory 
and practice, and may be properly called a science. 

THE LAWS OF GRAVITATION 

Suppose a one-pound weight is suspended by a 
string: there is a tensile stress in the string, varying 
slightly at different parts of the earth, but always 
the same at the same place, say, Newark, for the 
variation is very slight within a pretty wide area. 
If we take a spring balance and graduate it in 
pounds at Newark, such a balance will accurately 
indicate forces in pounds wherever it may be used. 
The stress produced in a string carrying a one-pound 
weight at Newark is the unit of force. If the 
string with its weight is hung from a nail, the nail 
is pressed on its upper side with a force of one pound. 
The same pressure may be produced by pushing 
the nail downwards from above, using a short piece 
of stick; in such circumstances, the stick bears a 
compression stress of one pound. This is a good, 
common-sense definition of force, though it does 
not by any means cover the whole subject. The 
word force is used in a different sense by persons 



£78 MECHANICS 

who speak of the force of gravity. When a one- 
pound weight is suspended by a string, as stated 
in the foregoing, the attraction between the mass 
of the weight and the mass of the earth is balanced 
by the stress in the string. We can double the 
stress by doubling the weight, and in this way, by 
adding weights, we can make the force of gravity 
very great. But the force of gravity is spoken of 
as an invariable thing, and it is said to be equal to 
32 (roughly). If any weight whatever be allowed 
to fall freely (for reasonable heights and neglecting 
the effect of the resistance of the air) it will be 
found that at the end of the first second it will 
have a velocity of 32 feet per second; at the end of 
the second second it will have a velocity of 64 
feet per second; and generally at the end of any 
number of seconds its velocity will be 32, and the 
rate of increase of velocity (acceleration) is 32 feet 
per second, all of which has been previously ex- 
plained. It is found convenient to call this accel- 
eration gravity — it is inaccurately called the 
force of gravity, it varies at different places on the 
earth. It is usual to designate the acceleration by 
the letter g, and we speak of the g, or gravity, of the 
place. This seems to cover the point of inquiry 
completely. 



SOME PRACTICAL ADVICE 279 

The subject of specific gravity is a far-reaching 
one, and includes the testing of liquors for revenue 
purposes and many other things of a scientific 
nature; but when we speak of specific gravity in 
an ordinary way we mean the comparative weight, 
bulk for bulk, of water at a certain temperature. 
The specific gravity of a substance like coal can be 
ascertained experimentally. By means of a spe- 
cially adapted and delicate balance, the sample of 
coal is first weighed in the ordinary way, after which 
it must be weighed suspended in a vessel of water. 
Weighed in water, it will be found the coal does not 
weigh so much. If the loss of weight, or the dif- 
ference between the first and second weighings be 
taken, and the first weighing divided by this loss 
of weight, we obtain the specific gravity of coal. 
For example, suppose a sample of coal weighs in 
the ordinary way 20 ounces, and in the water only 
four ounces, showing a loss of weight of 16 ounces. 
Divide 20 by 16, and we get the specific gravity of 
the sample of coal, viz., 1.25. 

The use of specific gravity is of great importance 
in mining, with regard to analysis of the minerals 
worked, for with a class of coal having the same 
relative composition, qualities, and calorific power 
per ton of coal employed for different purposes, 



280 MECHANICS 

yet having a higher specific gravity, the room re- 
quired for storage or transport will be less. This 
is an important factor, where there is limited space, 
as in depots and naval vessels. It is also employed 
in the arts and industries for many purposes, and is 
particularly useful to workers in precious metals, 
as the amount of alloy or baser metal may be de- 
termined by it that have been used in the manu- 
facture of jewellery, plate, and similar articles. 

To put it briefly: Specific gravity is the ratio 
of the heaviness of any substance to that of water. 
The specific gravity of water is taken as unity, 
and that of any other substance is expressed as a 
decimal. Tables of the weight and specific gravity 
of substances can be found in any good hand-book 
of engineering. 

HOW TO ADJUST SEWING MACHINES. 

Sewing machines often get out of order, and it 
is not always that an expert is at hand to adjust 
them, so a few general observations on the subject 
of these household machines may prove useful and 
interesting to every one who is at all mechanically 
inclined. 

There are several distinct types of machines, but 
we shall confine our remarks to the Singer vibrat- 



SOME PRACTICAL ADVICE 281 

ing shuttle, the hook shuttle types, and one or two 
others. To secure a perfect stitch in the vibrating 
shuttle machine, and to keep it from puckering thin 
goods, such as Japanese silks, muslins, and voiles, 
though possible, is difficult. Success depends en- 
tirely on the careful fitting of parts and the skilful 
adjustment of the machine to the particular fabric. 
In the first place, it is essential that a machine 
should work quite freely, a point not of such great 
importance if it is used for rougher classes of work. 
Machines used for domestic purposes, like theV. 
S. (vibrating shuttle), often stand unused for weeks 
together, so that the oil thickens and makes a ma- 
chine run somewhat heavily and unevenly. This 
may indirectly affect the regularity of the tension, 
especially with thin goods. Therefore, it is impor- 
tant to keep a machine clean and regularly oiled. 
Important parts are often overlooked during the 
operation; in fact, many users of machines do not 
know how nor where to oil one properly. There- 
fore Figs. 79 and 80 will be helpful, as they show 
the location of oil holes and parts to be oiled, and 
the illustrations will serve as a guide to other 
machines. In these figures, it will be seen that there 
are a number of parts to oil which could very easily 
be overlooked. When a machine has been unworked 



282 MECHANICS 

for a length of time, the appHcation of a little par- 
affin will cleanse the parts which should afterwards 
be oiled thoroughly with a good quality of machine 




Section showing oil holes 

oil. The shuttle raceway, where the shuttle works, 
should be wiped out with an oily rag. Any lint 
or dirt which has accumulated inside the shuttle 
at the nose end should be withdrawn, as such might 
retard the unwinding of the bobbin. It is imper- 
ative that the cotton should pull evenly, that is, 
free from jerks; this refers to the upper as well as 
to the lower tension. 

For silk and similar materials, best results can 
be obtained if fine cottons are used. Numbers 60, 
70, or 80 would be preferable to No. 40. A good 
quality of fine silk is even better. It must be remem- 
bered that when working on thin silk, say two 



SOME PRACTICAL ADVICE ^83 

thicknesses, a coarse cotton cannot be locked 
centrally. Fine cotton will need a fine needle, 
which necessitates a fine hole needle plate. 



^:M 




Fig. 80. Action of shuttle in the race 

If, after the foregoing points have been attended 
to, the machine runs easily, the parts fit properly, 
there is no end play to the upper shaft and the 
cottons pull evenly, yet the tensions are erratic, 
attention should be given to the loop as it draws 
off the shuttle heel. In machines of the C. B., 
O. S., and especially the V. S. class, there is a 
tendency for the loop to hang on the heel of the 
carrier, or to become trapped between the shuttle 
and the carrier heel. In the two former types 
of machines, the heel of the carrier should 
be rounded so as to induce the cotton to pass 
off as freely as possible. Sometimes it is nec- 
essary to time the shuttle a little later, that 
is, put the carrier back a little to allow the loop 



284 MECHANICS 

to draw off more in a line with the hole in the 
needle plate. 

In V. S. machines the carrier is already rounded 
off at the heel. By referring to Fig. 80, the action 
of the shuttle in the raceway can be seen, which 
is from A to B. The shuttle, having just entered 
the loop, is about to move to B. This movement 
can be regulated by an eccentric screw and nut 
(Fig. 80). When a machine has been taken to 
pieces and cleaned, this screw is not always replaced 
to the best advantage. If the shuttle moves too 
much toward B, the loop is carried by the heel 
of the carrier, and, at the same time, the shuttle 
cotton, by bearing tightly on the needle plate, 
pulls the shuttle toward the carrier heel, thus 
making it difficult for the loop to release itself. 
More tension is applied, perhaps more pressure is 
put on the take-up spring, yet the uneven tension 
is not overcome, and owing to the softness of the 
fabric, it is drawn up or puckered. The remedy 
is to turn the screw C (Fig. 80) , until the carrier is 
in a position to allow the loop a free exit. 

For such soft materials as mentioned it may be 
necessary to slacken both tensions. It should be 
remembered that the upper tension is generally 
somewhat tighter than the under one, and this 



SOME PRACTICAL ADVICE 285 

should be a guide to the adjustment of the latter, 
according to the fabrics to be stitched. 

To prevent puckering when the tensions are 
correct, reduce the pressure of the foot by loosen- 
ing the thumbscrew D (Fig. 79). Use a small 
size stitch — set the feed so that the teeth are just 
above the needle plate. Do not have the teeth 
too sharp, and if necessary, rub off the knife edge 
with F emery-cloth. Make the foot to bear squarely 
on the needle plate, and the feed square to the 
presser foot. Round off all sharp edges from the 
under side of the foot, especially the back edge. 
Special feeders are made for silk goods in machines 
used for factory work, which overcome the diffi- 
culty of puckering. 

By attention to the foregoing instructions, a 
machine should work easily, especially if the fabric 
is slightly pulled from behind the pressure foot. 

In C. B. machines, attention should also be 
given to the loop as it passes over the bobbin case 
and off the stop pin, it being necessary sometimes 
to round off the latter. If the tension spring screw 
projects too high or is rough, it may occasionally 
catch the cotton. 

The machine shown at Fig. 81 is of the '* Ro- 
tary Hook" — zigzag type. Its uses are similar to 



286 MECHANICS 

that of the oscillating shuttle type, but its con- 
struction is rather more complicated. 

The machine may be said to consist chiefly of 
an upper and a lower shaft, each having two cranks. 
In the vertical portion of the arm are two links 
which connect the shafts, causing them to work in 
unison with each other. The upper shaft gives 




Fig, 81. Rotary hook— Zigzag type 

motion by means of a cam and link to the needle 
bar and take-up lever; while the lower shaft, by 
means of three gear wheels, gives the rotary move- 
ment to the hook or shuttle, and by an eccentric 
cam and segment lever the necessary motion is 



SOME PRACTICAL ADVICE 287 

given to the feed or stitch mechanism. Figure 82 
shows the rocking frame into which the needle bar 
is fitted at A and B, while, at C and D, it is recessed 
to receive the taper ends of two screws, which pass 
through the face plate end of the machine arm. 
These screws are held secure by lock nuts, so 
screwed in as to allow the frame to rock freely. A 
ball-headed screw is fitted at E, to which is fastened 
a connection rod extending to a switch lever situated 
about the centre of the arm. This lever, by means 
of a cam movement, gives the vibrating motion 
to the needle bar, which can be regulated according 
to the relative position of the connection rod and 
lever. When the rod is at the bot- 
tom of the lever, a wide throw is 
obtained. By raising the rod a 
narrower throw is given, and if raised 
to the position shown in Fig. 81 no 
vibration will be given to the needle 
bar. The needle bar can be raised 
or lowered by loosening the screw 
that secures it to its link collar, 
which will be better seen by re- 
moving the face plate. Most needle 
bars have two marks upon them, and they should be 
set as follows: Remove the face plate, and turn the 




Fig. 82. Rocking 
frame 



288 MECHANICS 

hand wheel F (Fig. 81) toward you until the 
needle bar link has reached its lowest point of 
travel. 

Loosen the set screw of the needle bar collar, and 
set the needle bar so that its highest mark will 
be just level with the bottom of the rocking frame 
(Fig. 82). Then tighten the set screw, give the 
hand wheel a spin round, and again examine the 
position of the mark when the needle bar has 
reached its lowest point of travel, to make sure 
that no mistake has been made. Of course, it is 
necessary when parts are badly worn to set the 
needle bar a trifle lower, but this can be done after 
the foregoing rule has been adopted and proved a 
failure. In case of any unnecessary looseness in 
the middle bar or any of its connecting parts, they 
should be taken out and new parts fitted. The 
position of the needle may be altered to the right 
or left by loosening the screws G and H (Fig. 81), 
and adjusting the connection rod. Care should 
be taken not to set the connection rod too low down, 
or the needle may strike on the needle plate and 
cause trouble. 

Fig. 83 shows the face plate removed from the 
machine arm, A being a tension release lever. 
When the presser foot is lifted to its highest position, 



SOME PRACTICAL ADVICE 289 

the end of the lever goes between the tension disc, 
thus releasing all tension, so that materials can be 
taken from the machine without drawing slack 
cotton, or putting any unnecessary strain on the 
needle. When the presser foot is lowered, this 
lever should withdraw itself from the disc, thus 
allowing the proper tension to be put 
on the cotton. In some machines the 
withdrawal of this lever depends on 
a stud screw, fastened to the needle 
bar and projecting through the face 
plate. In the downward course of 
the needle bar this stud screw touches 
a spring, and causes the lever to trip 
backward. Should the spring be- 
come strained, or the stud screw be- Fig. 83. Section 

showing face plate 
come raised up a little, the release removed from ma- 
chine 

lever may remain between the disc 
and cause trouble. Sometimes it is necessary to 
bend the lever forward or backward to ensure 
its proper action. 

The hook or shuttle is rotary in motion. The 
hook (Fig. 84), is fitted to a ring, which is fixed 
to the hook guide (Fig. 85) by means of three small 
pins, and it is prevented from falling out by a steel 
cap secured with two screws and springs. The 






Fig. 84. Hook 
ring 



Fig. 85. Hook 
guide 



^90 MECHANICS 

hook is carried round by a driver (Fig. 86). Much 
depends on the hook, driver, and hook guide, 
so that a little detailed information is necessary. 
The hook driver must be a perfect fit 
in its bearings and free from sharp 
places where it comes in 
contact with the hook. 
The body of this driver is 
generally hardened, but the 
prong J (Fig. 86) is left 
soft so that it can be bent to meet requirements. 
When a machine is stitching, the hook driver 
rotates, and the prong J draws a given amount 
of slack cotton from the bobbin case. The farther 
this prong stands out, the more slack cotton it 

The prong may be bent 
inward, as shown by the 
dotted lines, but care must 
be taken not to drive it 
in so far as to allow the 
needle when descending, to 
strike on it, or to deviate 
from its true vertical posi- 
tion. Points K and L fit between the nose and 
neckvof the hook, while M comes against the heel. 
The hook is driven alternately by points K and M. 



draws off the bobbin. 



c 



■ liiALu I my.imwmKum llf, 




Fig. 86. Hook driver 



SOME PRACTICAL ADVICE 291 

When the hook is just entering the loop formed by the 
needle, it (the hook) is being driven by the driver 
wheel or M, and an opening is being made between 
point K and the hook nose for the free passage of 
the cotton. When the loop is being drawn off the 
hook by the takeup lever, the hook is driven by 
point K, and an opening is made between M and 
the heel of the hook for the exit of the cotton. 
There must always be sufficient clearance at points 
K, L, and M for the cotton or thread being used. As 
the heel of the driver M wears, the space at K will 
be reduced. Sometimes this can be remedied by 
bending the driver in at M, by giving it a blow with 
a hammer, placing a brass punch at M, but this 
should not be attempted if the driver is very hard. 
There is a means of adjustment provided in the 
hook guide (Fig. 85). This part is held in position 
by two set screws N and O. At the left of O is 
a small adjusting screw P. Supposing there is 
not sufficient space at point K (Fig. 86), for the 
cotton to pass, loosen the screw O (Fig. 85), 
and slightly tighten the screw P. This will tilt 
the hook guide and give more space. Should the 
screw P be turned in too far, the point L (Fig. 86), 
will be brought in contact with the narrow part 
of the hook near the neck, and this will impede 



292 MECHANICS 

its freedom, so that if allowed to run at much speed, 
the probable result will be the breaking of the hook 
oflF at the neck. This should be noticed in fitting 
a new hook, as the adjusting screw P (Fig. 85) 
will in all probability require loosening. The screws 
at N and O, however, must be kept quite tight. 
At each side of N is a small screw hole. The 
screws which fit here are for adjusting the hook 
closer to or farther from the needle. As an ex- 
ample, supposing a very fine needle has been used 
in the machine, and it is now required to take a 
very coarse one on account of the thick material 
to be stitched, the hook in all probability would 
strike the needle, indicating that the hook guide 
requires moving back a little. To do this, loosen 
the two small adjusting screws and tighten the set 
screw in N. Afterward try the set screw in O 
to ascertain if it is secure. In this way, the hook 
is thrown farther from the needle. Loosening the 
screw at N, and tightening the adjusting screws, 
will bring the hook forward. If the hook stands 
too far from the needle, it is likely to miss the loop. 
The hook nose must be well pointed and perfectly 
smooth, roughness or sharpness removed from any 
part of the hook over which the cotton passes during 
the formation of a stitch. 



SOME PRACTICAL ADVICE 293 

Hook rings are made in three sizes, numbers 
1, 2, and 3. Number 1 is for a new hook, numbers 
2 and 3 are for fitting as the hook wears. No 
matter what size of ring is used the hook must 
have perfect freedom. Sometimes the three pins 
in the guide draw the ring, and cause the hook to 
bind. It is best, therefore, to fix the ring to the 
guide, and then test the hook. If it is at all tight, 
grind it on the rim by means of an emery wheel or 
a grindstone. If neither is available, use number 
1 or number IJ^ emery cloth first, finishing with 
number 00 emery cloth. It is better to have the 
hook a little loose, even sluggish, than too tight. 
The timing of the hook will be dealt with later on. 

The bobbin case (Fig. 87), fixes to a stud in the 
centre of the hook. It is held in position, that is, 
kept from revolving with the hook, 
by means of a stop pin, Q, fitting --r^^^'J^V 
between a holder. The tension is j^^^m^lM^ 
obtained by a spring, R, which is ^m^^^^^ 
regulated by turning a small screw, ^^^^HS^ 
S, to the right to tighten and to the ^^^^^ 
left to loosen. Fig. 88 shows the 
bobbin case in position, with the holder raised ready 
for taking it out of the machine. Fig. 89 shows the 
bobbin in position in the bobbin case and method 



294 MECHANICS 

of threading, and Fig. 91, the direction the cotton 
should draw off the bobbin when it is in the machine. 




Fig. 88. Bobbin case in position 

It will be noticed that the 
cotton pulls in the opposite 
direction to which the hook 
travels, as shown by an arrow 
in Fig. 88. The bobbin case 
holder (Fig. 91), should pre- 
vent the bobbin case from 
revolving with the hook. 
As parts wear, the bobbin 
case is liable to slip past the holder, causing the 
cotton to be stranded and broken. When such is 




Fig. 89. Bobbin in position 
in bobbin case — Method of 
threading 



SOME PRACTICAL ADVICE 



295 




the case the holder should be bent as shown by 

(Fig. 92), but it must not fit so tightly against 

the bobbin case as to cause the 

cotton to become trapped. The 

holder is held rigid by means of 

a catch and spring T (Fig. 88). 

Should the catch or holder become 

^^ X u J • • ^ Fig. 90. Direction 

worn, nt new parts by driving out cotton should draw 

the pins U and V. Any sharpness or 

roughness on the forked part of the holder should be 

removed. Should the stop pin Q (Fig. 87) be- 
come loose, it should be soldered and 
well cleaned with an emery cloth. 
The centre tube of the bobbin case 
should also be kept quite firm. Should 
it become loose, place it over some 
hard substance, rivet it until tight. 
Figs. 91 and 92. and thoroughly smooth with very fine 

Bobbin case hold- 
ers emery cloth. 

The take up spring (Fig. 93) is attached to 

the face plate, and is shown in position in Fig. 

83. Replace a new one as follows: First take 

out the set screw W (Fig. 93), and remove the 

complete thread controller from the face plate. 

Then take out the screw and withdraw the old 

spring. Place the ring part of the new spring in 




MECHANICS 

the recess between plate Y and back plate Z, and 
replace the screw X, being careful not to get the 
spring fastened under the screw head. This done, 
fix the spring and other parts on the 
face plate. A small barrel with a 
slot in it receives the coiled portion 
of the spring. See that the part of 
the spring that is turned in enters 
the slot in the barrel, then replace 
the screw W, but before tightening 
this screw, see that the hooked part 
of the spring A' rests on the regula- 
tor B', which determines the amount of action given 
to the take-up spring. By raising it, less action 
is given. The amount of pressure on the spring 




Fig. 93. Take-up 
spring 




Figs. 94, 95, 



wmm 

Presser foot with details 



is regulated by adjusting the barrel in the face 
plate. Take oflF the face plate, loosen the screw C 



SOME PRACTICAL ADVICE 297 

(Fig. 83), fix a screwdriver in the rear of the bar- 
rel (seen inside the face plate), turn it toward 
you for more pressure, and backward for less and 
tighten the set screw C. 

Presser feet are made solid for ordinary purposes, 
although alternating feet can be fitted when desired. 
Figs. 94, 95, and 96 show a pressure foot, collar, 
and spring. To fix this foot, remove the ordinary 
presser foot, turn the foot bar round by loosening 
the set screw, so that the groove made for the re- 
ception of the presser foot is directly behind the 
needle. Put on the collar (Fig. 95), then turn 
the foot ](Pig. 94), and screw it in position. Next 
place the spring each side at the points Dl (Fig. 
94), press down the collar (Fig. 95), and secure 
it by its set screw. The springs will act on each 
half of the foot, and keep them firm, though the 
material be uneven. The foot is particularly use- 
ful when overseaming a hem or the top band of 
a lady's boot, etc. To time the hook and needle, 
raise the connection rod so as to produce no throw, 
and tighten the screw as in Fig. 81. Then take 
oflf the needle plate and remove the slide El (Fig. 
81) under which will be seen a crank and screws. 

Now turn the machine back as at Fig. 88, lift 
up the bobbin case holder by pressing the catch T, 



298 MECHANICS 

and remove the bobbin case. Take off the hook 
guide cap by removing the two screws. Turn the 
hand wheel F (Fig. 81), toward you, until the 
needle bar has descended to its lowest point of 
travel, and loosen the crank screw farthest from you. 
Having done this, continue turning the hand wheel 
until the needle bar has risen. With the lowest 
mark level with the rocking frame casting, at this 
point, examine the hook, the point of which should 
be just up to the needle. If otherwise, loosen the 
other screw in the crank under the plate El (Fig. 
81). Be sure the needle bar mark is level with the 
rocking frame, place the hook with its point just 
up to the needle, and tighten the crank set screw, 
being careful to have no end play to the short shaft. 
Again examine the needle bar and hook and if in 
proper time finally secure crank set screws and re- 
place the fittings previously removed. Thread the 
machine as indicated (Fig. 81). Set the needle 
as high in the bar as it will go, with the long groove 
facing the operator, and thread the needle from the 
long groove side. The stitch regulator will be found 
at F' (Fig. 81). The raising of it will shorten and 
the lowering of it will lengthen the stitch. The 
feed should be set about one thirty-second of an 
inch above the needle plate when at its highest 



SOME PRACTICAL ADVICE 299 

point. To raise the feed, turn the machine back 
as in Fig. 88. Near to the part Gl (Fig. 88) will 
be found a large set screw. Loosen it and press 
the lever Hi (Fig. 88) upward raising the feed 
bar Jl as high as required, and tighten the set screw 
at Gl firmly. To remove the feed for cleaning and 
sharpening, take off the needle plate, under which 
will be seen two feed set screws. By unscrewing 
these, the feed can be lifted out. 

One of the modern machines on the market is 
the Wheeler and Wilson, known as the Number 61, 
which is of rotary hook principle. The hook forms 
part of the under shaft, somewhat similar to that 
known as the D9 W and W. This hook and shaft 
revolves in two long bearings, and is held in position 
by a fluted wheel, which forms a collar at the right- 
hand end; thus when set properly no end play is 
permitted. This is an advantage over the boat- 
shaped shuttle machine. In the latter, the shuttle 
rocks about, becomes worn on the surface, often 
blunt pointed by striking the needle. As it wears, 
it becomes loose in the carrier, thus giving it freedom 
to roll away from or toward the needle, as well as 
making its action with relation to the needle very 
uncertain; and on account of the number of little 
loosenesses in fittings that this uncontrolled shuttle 



300 MECHANICS 

produces, missed stitches are frequent, and diffi- 
cult to remedy, unless a number of new fittings are 
obtained or old ones repaired. 

If there is any alteration required in the time of 
the rotary hook referred to, it can be made to the 
smallest fractional part of an inch very quickly and 
easily, and the movement can be relied on. The 
shaft to which it is secured is positive in its action 
(no variable motion), and at every stitch will meet 
the needle at exactly the same spot. This is an 
improvement over the boat-shaped shuttle, which 
has to have a certain amount of play or slackness 
to allow the loop to extricate itself; and this slack- 
ness increases as the machine is worked, so that 
the shuttle action often becomes very erratic. 

Sometimes a carrier becomes sprained at one end, 
thus allowing the shuttle too much freedom. If 
at the heel end, the carrier should be removed 
and placed in a vise (heel uppermost). The heel 
should be given a light blow with a hammer, thus 
bending it into correct position, but it must never 
be allowed to incline toward the shuttle; it should 
stand perfectly square, and have the upper corners 
rounded ojff. If inclined toward the shuttle, the 
loop may occasionally hang on the heel, and cause 
an irregular tension. 




Fig. 97. Bobbin case 
holder 



SOME PRACTICAL ADVICE 301 

In some machines the bobbin case holder (Fig. 
97) rests on the casting seen in Fig. 81. It is 
secured by a large set screw, D (Fig. 97). 
For general use, this screw should be adjusted to 
allow number 40 cotton to pass 
freely over the bobbin case. The 
holder should not be removed, ex- 
cept when adjustment or repair is 
needed. The vertical portion is 
hinged to the base, and is kept up- 
right by a lock spring and stud. If 
the spring is pressed from the stud, the vertical or 
ring part can be drawn back for placing in or 
taking out the bobbin case. The face of this 
portion must be perfectly square 
with the bottom of the base, other- 
wise it may cause considerable 
trouble. A slight adjustment can 
be made by loosening the two 
screws and moving the lock spring. A set square, 
E, should be used for testing the accuracy of this 
part as shown (Fig. 98), F representing the bobbin 
case holder. 

The thread controller is similar in design to 
several others, but its movement is regulated by a 
small lever (Fig. 99) which receives its motion 




Fig. 98. Set square 



302 MECHANICS 

from a link attached to the foot bar bracket set 
screw, and this may be seen through a hole in the 
face plate. At G (Fig. 99), this lever engages 
with a stop washer located behind the thread con- 
troller plate. The washer is recessed to form a 
stop, at the same time to give suflScient clearance 
for the action of the spring; thus as 



^^"^^ W the foot bar rises and falls, so does 
the thread controller spring. It is a 



^i, 



Fig. 99. Lever , . , i . 

common practice when cleanmg a 
machine to remove the face plate, thus detaching 
the link referred to, and not connecting it again 
when replacing the face plate. From this, trouble 
arises. The tension pulley should be placed on its 
stud, the large boss being toward the face plate. 

Thread a machine as follows: From the reel 
pin to nipper F (Fig. 81), round tension pulley 
G as the arrow indicates, down and into thread 
controller H up to take up lever, threading over the 
roll and through the slot from the top of lever, then 
down the thread guide J, into guide K, and through 
the needle eye from right to left. 

In the ordinary boat-shaped shuttle, the looping 
up of the thread is not difficult. The needle, as 
it descends, enters an opening or cavity in the car- 
rier, one side of which forms a support for the needle 



a 



SOME PRACTICAL ADVICE 303 

and guards it from contact with the shuttle point. 
Now, it is important that there be clearance for 
the needle. If the carrier stands so prominent 
as to spring the needle out of its true vertical line 
it will carry it away from the shuttle, and give the 
latter a chance to miss the loop. 

Then there are carriers and drivers of varying 
heights. Those of the raised kind are preferable, 
if properly fitted. By "raised" is meant that they 
are higher, so as to form a better guard for the 
needle, as previously referred to (Fig. 100 A, in 
which E indicates the portion of raised carrier, 
F the shuttle point, and G the needle). But some- 
times they are too 
high, and permit 
the needle eye to be 
buried in the car- 
rier, thus prevent- 
ing the proper for- 
mation of the loop. „ ' 
This can be so bad 

as to cause very Fig- lOO A, B, C, D. Carriers and drivers 

frequent missing; or it may be of such a slight 
character as to cause a miss-stitch only now 
and then. Occasionally, a needle bar has 
to be lowered, and that is suflScient to cause 




304 MECHANICS 

the same fault. The eye of the needle should al- 
ways be about one thirty -second of an inch above the 
upper edge of the carrier, and the latter should be 
shaped so as to allow that amount of clearance 
the whole of the time the needle is rising to form the 
loop, until the shuttle point has well entered the 
same. Pig. 100 B shows how a carrier is hollowed 
to give the necessary clearance to the needle- eye. 
When a machine is reasonably tight in all parts, 
gauges and setting marks may be adhered to for 




Sewing machine items 



the preliminary adjustments; and then if the ma- 
chine works erratically, other adjustments must be 
made. Where no marks or gauges are furnished 



! 



SOME PRACTICAL ADVICE 305 

for the adjustment of the needle bar, it should be 
so set as to allow the shuttle or hook to enter the 
bold part of the loop formed from the needle. A 
good rule is to set the needle bar so that the needle- 
eye is about %2 inch below the point of the shuttle 
M (Fig. 100 C) when the latter is up to the centre 
of the needle groove. But this may have to be 
varied from %4-inch to %2-inch. In boat-shaped 
and similar shuttle machines, a good rule is to 
set the needle so that the eye N will pass just below 
the lower side of the shuttle O as the latter is passing 
through the loop as in Fig. lOOD, P, indicating 
the level of the bed plate. 



II 

MECHANICAL MOVEMENTS 

WHAT is meant by this term is that these 
devices are intended for the transmission 
of motion. Motion in mechanics may be 
simple or compound. Simple motions are those 
of straight translation, which if of indefinite dura- 
tion must be reciprocating, or what is called 
oscillating or helical. 

Compound motions consist of combinations of 
any of the simple motions. Perpetual motion is 
an incessant motion conceived to be attainable 
by a machine supplying its own motive forces in- 
dependently of any action from without, or which 
has within itself the means, when once set in motion, 
of continuing its motion perpetually, or until 
worn out, without any new application of external 
force. The machine by means of which it has been 
attempted, or supposed possible to. produce such 
motion, is an invention much sought after, but 
physically impossible. 

The illustrations herewith exhibit a number of 

306 



MECHANICAL MOVEMENTS 307 

devices of various kinds, well known to the practical 
mechanician and professional engineer, and usually 
called mechanical movements. It is estimated 
there are no less than 1,500 of these movements 
doing service at the present day; but many of them 
are, of course, quite complex, and difficult to master. 
In this book, I show about one hundred of the sim- 
plest sort, or those in common use. Their useful- 
ness will at once be appreciated if we refer to Fig. 
102, which shows a machine for grinding or break- 
ing up substances within its capacity. It contains 
within itself the true principle of the little mill 
used to grind coffee. The word ''grind" in this 
connection is scarcely the right one, as the mill 
rather ''crushes" or breaks up, than grinds. You 
will notice coflFee, ready for use, is coarse and unlike 
flour in texture, the latter being "ground" fine and 
smooth. In grinding, the abrading surfaces are 
brought very much closer together than in the 
breaking or crushing processes. In a coffee mill, 
the berries or grains drop into a vacancy, left be- 
tween the revolving cone and the walls of the mill. 
The vacancy between the walls and the cone is a 
little less at the bottom where the crushed coffee 
is discharged, and this enables the small and 
large grounds to fall into the drawer. The detailed 



308 MECHANICS 

plan in illustration (Fig. 102) shows a mill complete, as 
well as the various parts. It will be noticed that 
the cone (Fig. 5), is corrugated or grooved as 
shown (Fig. 4). Figs. 6 and 7 show sections of 
lining at B and C (Fig. 3). A shows the hopper 
into which the coffee berries are placed before 
grinding. Figure 9 shows the crank detached, 
and Figs. 8 and 10 show the remaining parts of 




f«&, 



f I? II 

Kg. 102. Coffee mill and details 

the machine, while Figs. 1 and 2 show the handle 
and drawer. The latter is to receive the ground 
or crushed coffee after it has gone through the 
mill. Further description is unnecessary if we 
take for example the movement represented at 
Fig. 150, which is a sort of ball-bearing motion. 



MECHANICAL MOVEMENTS S09 

only instead of small balls wheels are used. Besides 
being made use of in bicycles in small balls, it is 
used as depicted for "hanging" grindstones, and 
for many other similar purposes. 

The device also shown at Fig. 139, is one in com- 
mon use. It is a modification of the sprocket wheel 
on the bicycle. Many of the devices shown herewith 
are rarely noticed because of our familiarity with 
them. 

The action of pumps, the working of pistons, the 
changing of motion, and many other things are 
shown and explained in the little illustrations given 
in these descriptions, which do not pretend to be 
exhaustive, or even full. 

Fig. 103. In this the lower pulley is movable. 
One end of the rope being fixed, the other has to 
move twice as fast as the weight, and a correspond- 
ing gain of power is consequently eflfected. 

Fig. 104 is a simple pulley used for lifting weights. 
In this the power must be equal to the weight to 
obtain equilibrium. 

Fig. 105. Blocks and tackle. The power ob- 
tained by this contrivance is calculated as follows : 
Divide the weight by double the number of pulleys 
in the lower block; the quotient is the power re- 
quired to balance the weight. 



310 MECHANICS 

Fig. 106 represents what are known as "White's 
pulley's, which can be made with separate loose 
pulley; or a series of grooves can be cut in a solid 
block, the diameters being made in proportion to 
the speed of the rope; that is, 1, 3, and 5 for one 
block, and 2, 4, and 6 for the other. Power as 1 to 7. 




Figs. 103, 104, 105, 106, 107. Various phases of block and tackle 

Figs. 107-108 are what are known as Spanish 
bartons. 

Fig. 108 is a combination of two fixed and one 
movable pulley. 

Figs. 111-113 are different arrangements of 
pulleys. The following rule applies to these: In 
a system of pulleys where each is embraced by a 
cord attached to one end of a fixed point, and at the 
other to the centre of the movable pulley, the effect 
of the whole will be the number 2 multiplied by 
itself as many times as there are movable pulleys 
in the system. 

Fig. 114. Endless chain for maintaining power 
on going barrel, to keep a clock going while winding, 



MECHANICAL MOVEMENTS 311 

as during that operation the action of the weight 
or main-spring is taken oflf the barrel. The wheel 






Figs. 108, 109, 110, 111, 112. Other combinations of blocks and pulleys 

to the right is the going wheel, and that to the 
left the striking wheel. P is a pulley fixed to the 
great wheel of the going part, and roughened to 
prevent a rope or chain hung over it from slipping. 
A similar pulley rides on another arbour, p, which 
may be the arbour of the great wheel of the striking 
part, attached by a ratchet and click to that wheel, 
or to the clock frame if there is no striking part. 
The weights are hung as may be seen, the small 
one being only large enough to keep the rope or 
chain on the pulleys. If the part b of the rope or 
chain is pulled down, the ratchet-pulley runs under 
the click, and the great weight is pulled up by c, 
without taking its pressure off the going wheel at all. 

Fig. 115. Triangular eccentric, giving an inter- 
mittent reciprocating rectilinear motion, often used 
for the valve motion of steam-engines. 



312 MECHANICS 

Fig. 116. Ordinary crank-motion. 

Fig. 117. In this, rotary motion is imparted to 





Figs. 113, 114, 115. Blocks and rocker 

the wheel by the rotation of the screw, or rectilinear 
motion of the slide by the rotation of the wheel. 
Used in screw cutting and slide lathes. 




Figs. 116, 117. Crank and rotary motion 

Fig. 118. Uniform circular into uniform recti- 
linear motion; used in spooling frames for leading or 
guiding the thread on to the spools. The roller 
is divided into two parts, each having a fine screw- 
thread cut upon it, one a right and the other a left- 
handed screw. The spindle, parallel with the roller, 
has arms which carry two half nuts, fitting to the 



MECHANICAL MOVEMENTS 313 

screw, one over the other under the roller. When 
one half nut is in, the other is out of gear. By 
pressing the lever to the right or left the rod is 
made to traverse in either direction. 

Fig. 119. A system of crossed levers, termed 
"lazy tongs." A short, alternating rectilinear 
motion of rod at the right will give a similar, but 
much greater motion to the rod at the left. It is 
frequently used in children's toys. It has been 
applied to machines for raising sunken vessels; 
also applied to ship pumps three quarters of a 
century ago. 




Figs. 118, 119. Rectilinear motion 

Fig. 120. Centrifugal governor for steam engines. 
The central spindle and attached arms and balls 
are driven from the engine by the bevel gears at 
the top, and the balls fly out from the centre by 
centrifugal force. If the speed of the engine in- 
creases, the balls fly out from the centre, raise the 
slide at the bottom, and thereby reduce the open- 



314 MECHANICS 

ing of the regulating valve, which is connected with 
the slide. A diminution of speed produces an 
opposite effect. 

Fig. 121. Water-wheel governor acting on the 
same principle as Fig. 120, but by different means. 
The governor is driven by the top horizontal shaft 
and bevel gears, and the lower gears control the 
rise and fall of the shuttle or gate over or through 
which the water flows to the wheel. The action 
is as follows: The two bevel gears on the lower 
part of the centre spindle, which are furnished with 
studs, are fitted loosely to the spindle, and remain 
at rest so long as the governor has a proper velocity; 
but immediately the velocity increases, the balls 
flying farther out, draw up the pin, which is attached 
to a loose sleeve which slides up and down the 
spindle, and this pin, coming in contact with the 
stud on the upper bevel gear, causes that gear to 
rotate with the spindle, and to give motion to the 
lower horizontal shaft in such a direction as to make 
it raise the shuttle or gate, and so reduce the quantity 
of water passing to the wheel. On the contrary, 
if the speed of the governor decreases below that 
required, the pin falls and gives motion to the lower 
bevel gear, which drives the horizontal shaft in the 
opposite direction, and produces a contrary effect. 



MECHANICAL MOVEMENTS 315 

Fig. 122. Another arrangement for a water-wheel 
governor. In this the governor controls the shuttle 
or gate by means of the cranked lever, which acts 
on the strap or belt in the following manner: The 
belt runs on one of three pulleys, the middle one of 
which is loose on the governor spindle, and the upper 
and lower ones fast. When the governor is running at 
the proper speed the belt is on the loose pulley, as 
shown; but when the speed increases, the belt is 
thrown on the lower pulley, and thereby caused to 
act upon suitable gearing for raising the gate or 
shuttle and decreasing the supply of water. A 
reduction of the speed of the governor brings the 
belt on the upper pulley, which acts upon the gearing 
for producing an opposite effect on the shuttle or 
gate. 

Fig. 123. Another form of steam-engine gov- 
ernor. Instead of the arms being connected with a 
slide working on a spindle, they cross each other, 
are elongated upward beyond the top, and con- 
nected with the valve-rod by two short links. 

Figs. 124, 125. Diagonal catch and hand-gear used 
in large blowing and pumping engines. In Fig. 
124 the lower steam valve and upper eduction 
valves are open, while the upper steam valve and 
lower eduction valve are shut; consequently the 



816 MECHANICS 

piston is ascending. In the ascent of the piston 
rod the lower handle will be struck by the pro- 
jecting tappet, and being raised will become en- 




Figs. 120, 121, 122, 123. Governors for steam-engines 

gaged by the catch, so as to shut the upper eduction 
and lower steam valves; at the same time the upper 
handle will be disengaged from the catch, the back 
weight will pull the handle up and open the upper 
steam and lower eduction valves, when the piston 
will consequently descend. Fig. 125 represents the 
position of the catches and handles when the piston 
is at the top of the cylinder. In going down, the 
tappet of the piston rod strikes the upper handle, 
and throws the catches and handles to the position 
shown in Fig. 124. 

Fig. 126. A mode of driving a pair of feed rolls, 
the opposite surface of which require to move in 
the same direction. The two wheels are pre- 
cisely similar, and both gear into the endless screw. 



MECHANICAL MOVEMENTS 317 

which is arranged between them. The teeth of 
one wheel only are visible, those of the other being 
on the back or side which is concealed from view. 






Kgs. 124. 125. 126. Valve Regulation and Feed Rolls 

Fig. 127. Link-motion valve gear of a locomotive; 
two eccentrics are used for one valve, one for the for- 
ward and the other for the backward movement of 
the engine. The extremities of the eccentric rods 
are jointed to a curved slotted bar, or, as it is termed, 
a link, which can be raised or lowered by an ar- 
rangement of levers terminating in a handle, as 
shown. In the slot of the link is a slide and pin 
connected with an arrangement of levers terminating 
in the valve stem. The link, in moving with the 
action of the eccentrics, carries with it the slide, 
and thence motion is communicated to the valve. 
Suppose the link raised so that the slide is in the 
middle, then the link will oscillate on the pin of the 
slide, and consequently the valve will be at rest. 
If the link is moved so that the slide is at one of 



318 MECHANICS 

the extremities, the whole throw of the eccentric 
connected with that extremity will be given to it, 
the valve and steam ports will be opened to the full, 
and it will only be toward the end of the stroke 
that they will be totally shut; consequently the 
steam will have been admitted to the cylinder dur- 
ing almost the entire length of each stroke. But 
if the slide is between the middle and the extremity 
of the slot, as shown in the figure, it receives only a 





Figs. 127, 128. Link and other motions 

part of the throw of the eccentric and the steam 
ports will only be partially opened, and quickly 
closed again, so that the admission of steam ceases 
some time before the termination of the stroke, and 
the steam is worked expansively. The nearer the 
slide is to the middle of the slot the greater will be 
the expansion, and vice versa. 

Fig. 128 represents a mode of obtaining motion 
from rolling contact. The teeth are for making 
the motion continuous, or it would cease at the 



MECHANICAL MOVEMENTS 319 

point of contact shown in the figure. The fork 
catch is to guide the teeth into proper contact. 

Fig. 129. What is called the Geneva-stop, used 
in Swiss watches to limit the number of revolutions 
in winding-up; the convex curved part of the 
wheel serving as the stop. 

Fig. 130. A continuous rotary motion of the large 
wheel gives an intermittent rotary motion to the 
pinion-shaft. The part of the pinion shown next 
the wheel is cut of the same curve as the plain 
portion of the circumference of the wheel, and 
therefore serves as a lock while the wheel makes a 
part of a revolution, and until the pin upon the 
wheel strikes the guide-piece upon the pinion, when 
the pinion-shaft commences another revolution. 




Figs. 129. 130. Stop and rotary motions 

Fig. 131. The two crank-shafts are parallel in 
direction, but not in line with each other. The 
revolution of either will communicate motion to the 
other with a varying velocity, for the wrist of one 



320 MECHANICS 

crank working in the slot of the other is continually 
changing its distance from the shaft of the latter. 
Figs. 132 and 133. These are parts of the same 
movement, which has been used for giving the 
roller motion in wool-combing machines The roller 
to which the wheel F,(Fig. 132) is secured, is required 
to make 3^ revolution backward, then ^ revolu- 




Figs. 131, 132, 133. Irregular Motions 

tion forward, when it must stop until another 
length of combed fibre is ready for delivery. This 
is accomplished by the grooved heart-cam C, D, B, 
e, (Fig. 133) the stud working in the said groove; 
from C to D it moves the roller backward, and from 
D to e it moves it forward, the motion being trans- 
mitted through the catch G, to the notch wheel F, 
on the roller-shaft H. When the stud A arrives at 
the point e in the cam, a projection at the back 
of the wheel, which carries the cam, strikes the pro- 
jecting piece on the catch G, and raises it out of the 
notch in the wheel F, so that while the stud is 



MECHANICAL MOVEMENTS 321 

travelling in the cam from e to C, the catch is pass- 
ing over the plain surface between the two notches 
in the wheel F, without imparting any motion; but 
when stud A arrives at the part C, the catch has 
dropped in another notch and is again ready to 
move wheel F and roller as required 

Fig. 134. An arrangement for obtaining variable 
circular motion. The sectors are arranged on differ- 
ent planes, and the relative velocity changes ac- 
cording to the respective diameters of the sectors. 

Fig. 135. Intermittent circular motion of the 
ratchet-wheel from vibratory motion of the arm 
carrying a pawl. 

Figs. 136. This represents an expanding pulley. 
On turning pinion d to the right or left, a 
similar motion is imparted to wheel c, by means 
of curved slots cut therein, which thrust the studs 




Figs. 135^ 134, 137, 136. Movements of various kinds 

fastened to arms of pulley outward or inward, 
thus augmenting or diminishing the size of the pulley. 



322 MECHANICS 

Fig. 137 represents a chain and chain pulley. 
The links being in different planes, spaces are left 
between them for the teeth of the pulley to enter. 

Fig. 138. Another kind of chain and pulley. 

Fig. 139. Another variety. 

Fig. 140 shows two different kinds of stops for 
a lantern- wheel. 




Figs. 140, 138, 189. Chain pulleys and lantern wheel 

Fig. 141. Intermittent circular motion is im- 
parted to the toothed wheel by vibrating the arm 
B . When the arm B is lifted, the pawl C is raised 
from between the teeth of the wheel, and travelling 
backward over the circumference again drops be- 
tween two teeth on lowering the arm, and draws 
with it the wheel. 

Fig. 142. The oscillating of the tappet-arm pro- 
duces an intermittent rotary motion of the ratchet- 
wheel. The small spring at the bottom of the tappet 
arm keeps the tappet in the position shown in the 
drawing, as the arm rises, yet allows it to pass the 
teeth on the return motion. 



MECHANICAL MOVEMENTS 323 

Fig. 143. A nearly continuous circular motion is 
imparted to the ratchet-wheel on vibrating the 
lever a to which the two pawls h and c are attached. 




Figs. 141, 142, 143. Intermittent circular motion 

Fig. 144. An arrangement of stops for a spur- 
gear. 

Fig. 145. A reciprocating circular motion of the 
top arm makes its attached pawl produce an in- 
termittent circular motion of the crown-ratchet, 
or ray-wheel. 




Figs. 144, 145. Intermittent circular motion 

Fig. 146 represents varieties of stops for ratchet- 



wheel. 



Fig. 147. Intermittent circular motion is im- 



324 MECHANICS 

parted to the wheel A by the continuous circular 
motion of the smaller wheel with one tooth. 





Figs. 146» 147. Ratchet motion 

Fig. 148. A dynamometer, or instrument used 
for ascertaining the amount of useful effect given 
out by any motive power. It is used as follows: 
A is a smoothly turned pulley, secured on a shaft 
as near as possible to the motive power. Two 
blocks of wood are fitted to this pulley, or one 
block of wood and a series of straps fastened to a 
band or chain, as in the drawing, instead of a common 
block. The blocks, or block and straps, are so 
arranged that they may be made to bite or press 
upon the pulley by means of the screws and nuts 
on the top of the lever D. To estimate the amount 
of power transmitted through the shaft, it is only 
necessary to ascertain the amount of friction of 
the drum A when it is in motion, and the number of 
revolutions made. At the end of the lever D is 
hung a scale B, in which weights are placed. The 



MECHANICAL MOVEMENTS 325 

two stops C C are to maintain the lever as nearly 
as possible in a horizontal position. Now, suppose 
the shaft to be in motion, the screws are to be tight- 
ened and weights added in B, until the lever takes the 
position shown in the drawing, at the required 
number of revolutions. Therefore the useful eflFect 
would be equal to the product of the weights, 
multiplied by the velocity at which the point or 
suspension of the weights would revolve if the 
lever were attached to the shaft. 

Fig. 149 represents a panta graph for copying, 
enlarging and reducing plans. One arm is at- 
tached to and turns on the fixed point C. B is an 
ivory tracing point, and A the pencil. Arranged 
as shown, if we trace the lines of a plan with the 
point B, the pencil will produce it double the size. 




ec 





Kgs. 148, 149. Dynamometer — Pantagraph 

By shifting the slide attached to the fixed point C 
and the slide carrying the pencil along their respec- 
tive arms, the proportions to which the plan is 
traced will be varied. 



326 MECHANICS 

Fig. 150. Anti-friction bearing. Instead of a 
shaft revolving in an ordinary bearing, it is some- 
times supported on the circumference of wheels. 
The friction is thus reduced to the least amount. 

Fig. 151. Releasing hook used in pile-driving 
machines. When the weight W is sufficiently raised, 
the upper ends of the hooks A, by which it is sus- 
pended, are pressed inward by the side of the slot 
B, in the top of the frame; the weight is thus sud- 
denly released, and falls with accumulating force 
on to the pile-head. 

Fig. 152. A and B are two rollers which require 
to be equally moved to and fro in the slot C. This 
is accomplished by moving the piece D, with oblique 
slotted arms, up and down. 

c 





il— u 

Figs. 150, 151. 152. Anti-friction — Drop hook — Regular motion 

Fig. 153. Centrifugal check-hooks, for prevent- 
ing accidents in case of the breakage of machinery 
which raises and lowers workmen, or ores, in mines. 
A is a framework fixed to the side of the shaft of 



MECHANICAL MOVEMENTS 327 

the mine, and having fixed studs D, attached. 
The drum on which the rope is wound is provided 
with a flange B, to which the check-hooks are 
attached. If the drum acquires a dangerously 
rapid motion, the hooks fly out by centrifugal force, 
and one or other, or all of them, catch hold of the 
studs D, arrest the drum, and stop the descent of 
whatever is attached to the rope. The drum 
ought besides this, to have a spring applied to it, 
otherwise the jerk arising from the sudden stop- 
page of the rope might produce a worse effect than 
its rapid motion. 

Fig. 154. A sprocket-wheel to drive or to be 
driven by a chain. 

Fig. 155. A combination movement, in which 
the weight W moves with a reciprocating move- 
ment, the down-stroke being shorter than the 
up-stroke. B is a revolving disc, carrying a drum 
which winds around itself the cord D. An arm C 
is jointed to the disc and to the upper arm A, so 
that when the disc revolves, the arm A moves up 
and down, vibrating on the point G. This arm 
carries with it the pulley E. Suppose we detach 
the cord from the drum, tie it to the fixed point, 
and then move the arm A up and down. The 
weight W will move the same distance, and in 



328 MECHANICS 

addition the movement given it by the cord, that 
is to say, the movement will be doubled. Now, 
let us attach the cord to the drum, and revolve the 
disc B, and the weight will move vertically with 
the reciprocating motion, in which the down stroke 
will be shorter than the up-stroke, because the drum 
is continually taking up the cord. 




^ 



p 




A 



Figs. 153, 154, 155. Hooks — Sprocket — Combination movement 

Figs. 156, 157. The first of these figures is an 
end view, and the second is a side view of an ar- 
rangement or mechanism for obtaining a series of 
changes in velocity and direction. D is a screw on 
which is placed eccentrically the cone B, and C is 
a friction roller, which is pressed against the cone 
by a spring or weight. Continuous rotary motion, 
at a uniform velocity of the screw D carrying the 
eccentric cone, gives a series of changes of velocity 
and direction to the roller C. It will be under- 
stood that during every revolution of the cone the 
roller would press against a different part of the cone, 



MECHANICAL MOVEMENTS 

and that it would describe thereon a spiral motion, 
the movement in one direction being shorter than 
that in the other. 




Figs. 156, 157. Change of speed 

Fig. 158. An engine governor. The rise and fall 
of the balls K are guided by the parabolic curved 
arms B, on which the anti-friction wheels L run. 
The rods F, connecting the wheel L with the sleeve, 
move it up and down the spindle C D. 

Fig. 159. Toe and lifter for working poppet- 
valves in steam engines. The curved toe on the 
rock-shaft operates on the lifter attached to the 
lifting rod to raise the valve. 

Fig. 160. Mercurial compensation pendulum. A 
glass jar of mercury is used for the bob or weight. 
As the pendulum-rod is expanded lengthwise by 
increased temperature, the expansion of mercury 
in the jar carries it to a greater height therein, 
and so raises its centre of gravity relatively to the 



330 MECHANICS 

rod suflBciently to compensate for downward ex- 
pansion of the rod. As rod is contracted by a 
reduction of temperature, contraction of mercury 
lowers it relatively to rod. In this way the centre 
of oscillation is always kept in the same place, and 
the effective length of pendulum always the same. 



c:Q^ 




r-f 




Figs. 158, 159, 160. Governor, lifter, and pendulum 

Fig. 161. Compound bar compensation pendu- 
lum. C is a compound bar of brass and iron, 
or steel brazed together with brass downward. 
As brass expands more than iron, the bar will bend 
upward as it gets warmer, and will carry the weights 
W, W, up with it, raising the centre of the aggre- 
gate weight M, to raise the centre of oscillation as 
much as elongation of the pendulum-rod would 
let it down. 

Fig. 162. Watch regulator. The balance-spring 
is attached at its outer end to a fixed stud R, and 
at its inner end to staff of balance. A neutral 
point is formed in the spring at P, by inserting it 



MECHANICAL MOVEMENTS 331 

between two curb-pins in the lever, which is fitted 
to turn on a fixed ring concentric with staflf of 
balance, and the spring only vibrates between this 
neutral point and stafif of balance. By moving 
lever to the right, the curb-pins are made faster, 
and by moving it to the left, an opposite effect is 
produced. 





AST 



Figs. 161, 162. Compound bar — Hair spring 

Fig. 163. Compensation balance, t, a, t' is the 
main bar of balance, with timing screws for regula- 
tion at the ends, t and t^ are two compound 
bars, of which the outside is brass and the inside 
steel, carrying weights &, V. As heat increases, 
these bars are bent inward, diminishing the inertia 
of the balance. As the heat diminishes, an op- 
posite eJBFect is produced. This balance compen- 
sates both for its own expansion and contraction, 
and that of the balance-spring. 

Fig. 164. Parallel ruler, consisting of a simple 



332 MECHANICS 

straight ruler B, with an attached axle C, and a 
pair of wheels A A. The wheels, which protrude 
but slightly through the under side of the ruler, 
have their edges nicked to take hold of the paper 
and keep the ruler always parallel with any lines 
drawn upon it. 







< CT^'^ ^ A 



Figs. 163. 164. Balance — Ruler 

Fig. 165. Compound parallel ruler, composed of 
two simple rulers A, A, connected by two crossed 
arms pivoted together at the middle of their length, 
each pivoted at one end to one of the rulers, and 
connected with the other one by a slot and sliding 
pin, as shown at B. In this the ends as well as 
the edges are kept parallel. The principle of 
construction of the several rulers represented is 
taken advantage of in the formation of some parts 
of machinery. 

Fig. 166. A simple means of guiding or obtaining 
a parallel motion of the piston rod of an engine. 
The slide a moves in and is guided by the vertical 



MECHANICAL MOVEMENTS 



333 



slot in the frame, which has been planed to a true 
surface. 



^ 




^ 




Figs. 165, 166. Ruler — Parallel motion 

Fig. 167. Parallel motion for direct-action en- 
gines. In this, the end of the bar B C is connected 
with the piston-rod, and the end B slides in a fixed 
slot D. The radius bar F A is connected at F 
with a fixed pivot, and at A midway between the 
ends of B C. 

Fig. 168. Oscillating engine. The cylinder has 
trunnions at the middle of its length, working in 






Figs. 167, 168, 169. Parallel motion methods 

fixed bearings, and the piston rod is connected 
directly with the crank, and no guides are used. 



334 MECHANICS 

Fig. 169. Inverted oscillating or pendulum en- 
gine. The cylinder has trunnions at its upper end, 
and swings like a pendulum. The crank shaft is 
below, and the piston rod connected directly with 
crank. 

Fig. 170. Section of disc-engine. Disc-piston, 
seen edgewise, has a motion substantially like a 
coin when it first falls after being spun in the air. 
The cylinder heads are cones. The piston rod is 
made with a ball to which the disc is attached, 
said ball working in concentric seats in cylinder- 
heads, and the left-hand end is attached to the 
crank arm or fly-wheel on end of shaft at left. 
Steam is admitted alternately on either side of 
piston. 

Fig. 171. The gyroscope, or rotascope, an in- 
strument illustrating the tendency of rotating bodies 
to preserve their plane of rotation. The spindle 
of the metallic disc C is fitted to return easily in 
bearings in the ring A. If the disc is set in rapid 
rotary motion on its axis, and the pintle F at one 
side of the ring A is placed on the bearing in the 
top of the pillar G, the disc and ring seem indifferent 
to gravity, and instead of dropping begin to revolve 
about the vertical axis. 

Fig. 172. Bohnenberger's machine, illustrating 



MECHANICAL MOVEMENTS 



S35 



the same tendency of rotating bodies. This con- 
sists of 3 rings, A, A\ A%, placed one within the 
other, and connected by pivots at right angles to 
each other. The smallest ring, ^2, contains the 
bearings for the axis of a heavy ball B. The ball 
being set in rapid rotation, its axis will continue in 
the same direction, no matter how the position of 
the rings may be altered; and the ring A2, which 
supports it, will resist a considerable pressure tend- 
ing to displace it. 




Figs. 170, 171, 172. Disc-engine and gyroscopes 

Fig. 173. What is called the gyroscope governor, 
for steam-engines, introduced by Alban Anderson 
in 1858. A is a heavy wheel, the axle B B' of 
which is made in two pieces connected together 
by a universal joint. The wheel A is on one piece 
B, and a pinion 1 on the other piece B'. The 
piece B is connected at its middle by a hinge- joint 
with the revolving frame ff, so that variations in 
the inclination of the wheel A will cause the outer 



MECHANICS 

end of the piece J? to rise and fall. The frame H 
is driven by bevel gearing from the engine, and 
by that means the pinion 1 is carried round the 
stationary toothed circle G, and the wheel A is thus 
made to receive a rapid rotary motion on its axis. 
When the frame H and wheel A are in motion, the 
tendency of the wheel A is to assume a vertical 
position, but this tendency is opposed by a spring 
L. The greater velocity of the governor, the 
stronger the tendency, above mentioned, and the 
more it overcomes the force of the spring, and the 
reverse. The piece B is connected with the valve 
rods by rods C, D, and the spring L is connected 
with the said rods by levers N and rod P. 




Figs. 173, 174, 175. Governor — Reverse motions 

Fig. 174. Pair of edge runners, or chasers for 
crushing or grinding. The axles are connected 
with vertical shaft, and the wheel or chasers run 
in an annular pan or trough. 

Fig. 175. Rotary motion of shaft from treadle 



MECHANICAL MOVEMENTS 837 

by means of an endless band running from a roller 
on the treadle to an eccentric on the shaft. 

Fig. 176. Tread- wheel horse-power turned by the 
weight of an animal attempting to walk up one 
side of its interior; has been used for driving the 
paddle-wheels of ferry-boats and many other pur- 
poses. The turn-spit dog used also to be employed 
in such a wheel in ancient times for turning meat 
while roasting on a spit. 

Fig. 177. The treadmill, employed in jails in 
some countries for exercising criminals condemned 
to labour, and employed in grinding grain; turns by 
weight of person stepping on tread-boards on 
periphery. This is supposed to be a Chinese in- 
vention, and it is still used in China for raising 
water for irrigation. 

Fig. 178. A. B. Wilson's four-motion feed, used 
in Wheeler and Wilson's, Sloat's, and other sewing 




Figs. 176» 177, 178. By different sources of power 

machines. The bar A is forked, and has a second 
bar B, carrying the spur or feeder, pivoted in the 



338 MECHANICS 

said fork. The bar B is lifted by a radial projection 
on the cam C, at the same time the two bars are 
carried forward. A spring produces the return 
stroke, and the bar B drops of its own gravity. 

Fig. 179. Mechanical means of describing par- 
abolas, the base, altitude, focus, and directrix 
being given. Lay straight edge with near side 
coinciding with directrix, and square with stock 
against the same, so that the blade is parallel with 
the axis, and proceed with pencil in bight of thread, 
as in the preceding. 

Fig. 180. Mechanical means of describing hyper- 
bolas, their foci and vertices being given. Suppose 
the curves two opposite hyperbolas, the points in 
vertical dotted centre line their foci. One end of 





Figs. 179, 180. To describe conic sections 

thread being looped on pin inserted at the other 
focus, and other end held to other end of rule, with 
just enough slack between to permit height to 
reach vertex when rule coincides with centre line. 
A pencil held in bight, and kept close to the rule, 



MECHANICAL MOVEMENTS 339 

while latter is moved from centre line, describes 
one-half of parabola; the rule is then reversed for 
the other half. 

Fig. 181. Cyclograph for describing circular arcs 
in drawings where the centre is inaccessible. This 
is composed of three straight rules. The cord and 
versed sine being laid down, draw straight, sloping 
line from ends of former to top of latter; and to 
these lines lay two of the rules crossing at the 
apex. Fasten these rules together, and another 
rule across them to serve as a brace, and insert a 
pin or point at each end of chord to guide the ap- 
paratus, which, on being moved against these points, 
will describe the arc by means of pencil in the 
angle of the crossing edges of the sloping rules. 

Fig. 182. Proportional compasses used in copy- 
ing drawings on a given larger or smaller scale. The 
pivot of compasses is secured in a slide which is 
adjustable in the longitudinal slots of legs, and 
capable of being secured by a set screw; the di- 
mensions are taken between one pair of points and 
transferred with the other pair, and thus enlarged 
or diminished in proportion to the relative dis- 
tances of the points from the pivot. A scale is 
provided on one or both legs to indicate the 
proportions. 



340 MECHANICS 

Fig. 183. One of the many forms of rotary en- 
gine. A is a cylinder having the shaft B pass 
centrally through it. The piston C is simply an 
eccentric fast on the shaft, and working in con- 
tact with the cylinder at one point. The in- 
duction and eduction of steam take place as in- 
dicated by arrows, and the pressure of the steam 
on one side of the piston produces its rotation and 
that of the shaft. The sliding abutment D, be- 
tween the induction and eduction ports, moves 
out of the way of the piston to let it pass. 





Figs. 181, 182, 183. For drawing curves. Rotary engine 

Fig. 184. Another form of rotary engine, in which 
there are two stationary abutments D, D, within 
the cylinder; and the two pistons A, A, in order to 
enable them to pass the abutments, are made to 
slide radially in grooves in the hub C of the main 
shaft B. The steam acts on both pistons at once, 
to produce the rotation of the hub and shaft. The 
induction and eduction are indicated by arrows. 



MECHANICAL MOVEMENTS 



341 



Fig. 185. Jonval turbine. The shutes are ar- 
ranged on the outside of a drum, radial to a common 
centre, and stationary within the trunk or casing 
b. The wheel c is made in nearly the same way; 
the buckets exceed in number those of the shutes, 
and are set at a slight tangent instead of radially, 
and the curve generally used is that of the cycloid 
or parabola. 

Fig. 186. A method of obtaining a reciprocating 
motion from a continuous fall of water, by means 
of a valve in the bottom of the bucket which opens 
by striking the ground, and thereby emptying the 
bucket, which is caused to rise again by the action 
of a counterweight on the other side of the pulley 
over which it is suspended. 



O 






a 



Figs. 184, 185, 186. Different forms of water movements 

Fig. 187. Overshot water-wheel. 

Fig. 188. Undershot water-wheel. 

Fig. 189. Breast-wheel. This holds intermediate 



342 MECHANICS 

place between overshot and undershot wheels; has 
float-boards like the former, but the cavities be- 
tween are converted into buckets by moving in a 
channel adapted to circumference and width, into 
which water enters nearly at the level of axle. 
Fig. 190. Horizontal overshot water-wheel. 




Figs. 187, 188, 189, 190. Water-wheels 

Fig. 191. A plan view of the Fourneyron tur- 
bine water-wheel. In the centre are a number of 
fixed curved chutes, or guides, A, which direct the 
water against the buckets of the outer wheel B, 
which revolves, and the water discharges at the 
circumference. 

Fig. 192. Warren's central discharge turbine, 
plan view. The guides A are outside, and the wheel 
B revolves within them, discharging the water at 
the centre. 

Fig. 193. Volate wheel, having radial vanes A, 
against which the water impinges and carries 
the wheel around. The scroll or volute casing B 
confines the water in such a manner that it acts 
against the vanes all around the wheel. By the 



MECHANICAL MOVEMENTS 343 

addition of the inclined buckets c, c, at the bottom, 
the water is made to act with additional force as it 
escapes through the openings of said buckets. 






Figs. 191, 192, 193. Central discharge and turbine wheels 

Fig. 194. Barker, or reaction mill. Rotary mo- 
tion of central hollow shaft is obtained by the 
reaction of the water escaping at the ends of its 
arms, the rotation being in a direction the reverse 
of the escape. 

Fig. 195 represents a trough divided transversely 
into equal parts, and supported on an axis by a 
frame beneath. The fall of water filling one side 
of the division, the trough is vibrated on its axis, 
and at the same time that it delivers the water 
the opposite side is brought under the stream and 
filled, which in like manner produces the vibration 
of the trough back again. This has been used as 
a water-meter. 

Fig. 196. Persian wheel, used in Eastern coun- 
tries for irrigation. It has a hollow shaft and 



344 MECHANICS 

curved floats, at the extremities of which are 
suspended buckets or tubs. The wheel is partly 
immersed in a stream acting on the convex surface 
of its floats; and as it is thus caused to revolve, a 
quantity of water will be elevated by each float 
at each revolution, and conducted to the hollow 
shaft at the same time that one of the buckets 
carries it full of water to a higher level, where it is 
emptied by coming in contact with a stationary 
pin placed in a convenient position for tilting it. 






Figs. 194, 195, 196. Water motors 

Fig. 197. Machine of ancient origin, still employed 
on the river Eisach, in the Tyrol, for raising water. 
A current keeping the wheel in motion, the pots 
on its periphery are successively immersed, filled, 
and emptied into a trough above the stream. 

Fig. 198. Application of Archimedes screw for 
raising water, the supply stream being the motive 
power. The oblique shaft of the wheel has ex- 
tending through it a spiral passage, the lower end 



MECHANICAL MOVEMENTS 345 

of which is immersed in water, and the stream 
acting upon the wheel at its lower end produces 
its revolution by which the water is conveyed 
upward continuously through the spiral passage 
and discharged at the top. 

Fig. 199. Common lift pump. In the upper- 
stroke of piston or bucket the lower valve opens 
and the valve in piston shuts; air is exhausted out of 
suction pipe, and water rushes up to fill the vacuum. 
In down stroke lower valve is shut and valve in 
piston opens, and the water simply passes through 
the piston. The water above piston is lifted up, 
and runs over out of spout at each up stroke. This 
pump cannot raise water over thirty feet high. 





Figs. 197, 198, 199. Water-wheels and pumps 

Fig. 200. Ordinary force pump, with two valves. 
The cylinder is above water, and is fitted with solid 
piston; one valve closes outlet pipe, and other 
closes suction pipe. When piston is rising suction- 
valve is open, and water rushes into cylinder, out- 



346 



MECHANICS 



let valve being closed. On descent of piston suc- 
tion valve closes, and water is forced up through 
outlet valve to any distance or elevation. 

Fig. 201. Double-acting pump. Cylinder closed 
at each end, and piston-rod passes through stuffing- 
box on one end, and the cylinder has four openings 
covered by valves, two for admitting water and 
like number for discharge. A is suction pipe, and 
B discharge pipe. When piston moves down, water 
rushes in at suction valve 1, on upper end of cyl- 
inder, and that below piston is forced through valve 
3 and discharge pipe B; on the piston ascending 
again, water is forced through discharge valve 4, 
on upper end of cylinder, and water enters lower 
suction valve 2. 

Fig.^202. Common windmill, illustrating the pro- 






Figs 200, 201, 202. Pumps and windmill 

duction of circular motion by the direct action of 
the wind upon the oblique sails. 

Fig. 203. Ordinary steering apparatus. Plan 



MECHANICAL MOVEMENTS 



347 



view. On the shaft of the hand wheel, there is a 
barrel on which is wound a rope, which passes 
round the guide-pulleys, and has its opposite ends 
attached to the tiller, or lever, on top of the rudder; 
by turning the wheel, one end of the rope is wound 
on and the other left off, and the tiller is moved in 
one or the other direction, according to the direction 
in which the wheel is turned. 

Fig. 204. Capstan. The cable or rope wound 
on the barrel of the capstan is hauled in by turning 
the capstan on its axis by means of handspikes or 
bars inserted into holes in the head. The capstan 
is prevented from turning back by a pawl attached 
to its lower part and working in a circular ratchet 
on the base. 




Fig. 203. Cable. 




Fig. 204. Capstan 



Fig. 205. Lewis bolt for lifting stone in building. 
It is composed of a central taper-pin or wedge, 
with two wedge-like packing pieces arranged one 
on each side of it. The three pieces are inserted 



348 MECHANICS 

together in a hole drilled into the stone, and when 
the central wedge is hoisted upon it, it wedges the 
packing pieces out so tightly against the sides of 
the hole as to enable the stone to be lifted. 

Fig. 206. Tongs for lifting stones. The pull 
on the shackle which connects the two links causes 
the latter so to act on the upper arms of the tongs 





Figs. 205, 206. Lewis bolts, for lifting stones 

as to make their points press themselves against 
or into the stone. The greater the weight, the 
harder the tongs bite. 



m 

THE WEATHER AND INDOOR WORK 

THE measure of rainfall varies considerably 
within comparatively small areas, and this 
renders it no easy matter to get correct 
figures, so that the nearest records are those taken 
from a number of gauges within a limited district, 
and generalized. The more this is done, the less 
will be the inaccuracy in referring to the rainfall 
of any particular district or country. 

If numerous rain-gauges were established through- 
out the country, and all their records sent to one 
central station, what valuable information might 
be collected for a particular district or country 
in the course of years. Means might be found for 
using the superabundant water, which falls in one 
part over another part, where the rainfall is less. 
Information such as this might be of special value 
in the West and South. It is collected now to a 
certain extent; but not done so generally as it ought 
to be. 

As the fall of rain is always measured in inches 

S49 



350 MECHANICS 

gauges are made to indicate the equivalent of a cubic 
inch of rain on the surface of the earth. The sim- 
plest form of rain-gauge is a square or circular box 
or jar with a perfectly flat bottom and perpendicular 
sides (see Fig. 207). If the depth of water in such 
a gauge be measured after a fall of rain, one can 
ascertain in inches, or parts of an inch, the amount 
of rain that has fallen on the surface of the earth. 
Care must be taken to have the edge of the gauge 
thin and free from dents, the sides perpendicular 
and the bottom of the jar perfectly flat, for though 
in one measurement these irregularities may not 

make much difference, they 
would lead to a very decided 
error in a large number of 
measurements. Evaporation is 
also liable in such a gauge to 
give rise to errors, and extra- 
neous matters are easily intro- 
duced. The better rain-gauges 
are constructed to. avoid these 
^ -^.:Er-:^I--r:-.'-cL^ contingencies, as far as possible 
Fig. 207. Rain gauge and to dcpcud Only ou the area 
of entry for the accuracy of the measurements. 
This area may be a square, but is usually 
circular for convenience. The circle must be 




THE WEATHER AND INDOOR WORK 351 
accurate, and its area is then easily calculated, 
so that one can estimate the amount of 
rainfall, however large the receiving vessel may 
be. The edge of the circle, which may be made 
of copper, more durable than iron, must be 
sharp, with an overlapping rim to prevent raindrops 
from being whirled out of the receiver, and connected 
by a shoulder to a funnel, which directs the water 
into the receiver. This 
may be a glass bottle fitted 
with a cork to hold the 
funnel firmly, and prevent 
leakage between the outside 
of the funnel and the neck 
of the bottle (see Fig. 208). 
A more convenient receiver, 
and one less likely to be 
broken, is a round tin case 
of convenient size, with a 
top fitting accurately under 
the overlapping edge of the 
funnel-shaped cover. In 
this large receiver may be 

placed a small tin mug, ^e- 2O8. a made rain-guage 

with a lip just under the funnel, for conveniently 
measuring small quantities of rain, and prevent- 




i 



35^ MECHANICS 

ing waste by evaporation. Any overflow from 
the mug will be caught in the large receiver 
(see Fig. 209). The circle of entry may, of 
course, be of any size; but one whose diameter 
is between 4 or 8 inches will be most convenient. 
Make the circle determine its area by careful meas- 

urement, using the following formula: D 
.7854 = area, each square inch will give cubic inches 

for area. Take this 
amount of water and 
pour it into a glass, 
marked at the top of the 
water, and then divide 
the intervening space 
between this mark and 
the bottom into 100 
equal parts. This grad- 
uated glass will give 
the rainfall in inches and 
lOOths of an inch. As 
an inch glass is some- 
what cumbersome, a 
half-inch glass is usually sent out with a rain- 
gauge. It may, however, be sometimes con- 
venient to use an ordinary ounce measure, as 




Fig. 209. A more complete rain- 
gauge 



THE WEATHER AND INDOOR WORK 353 

graduated glass measures, when broken, are not 
always easily replaced; so that it may be necessary 
to find the corresponding relation between the cubic 
inches of receiving area and ounces and drachms. 
To do this, we will suppose the diameter of the 
circular top of gauge to be 4.7 inch; this squared 
= 22.09, multiplied by .7854 = 17.349486, divided 
by 1:733 (an ounce avoir. = 1.733 c. in.) = 10.011 
oz. avoir. 

Now if the rainfall is collected daily at a certain 
time in an ounce measure, the amount may easily 
be recorded in inches by reference to the accompany- 
ing table: 

inch 
1.0000 1 

.9000 7 

.8000 6 

.7000 5 

.6000 4 

.5000 3 

.4000 2 

.3000 1 

.2000 

A similar calculation can be made and table 
prepared for any larger circle of entry by the same 
method. 



10 


oz 


9 




8 




7 




6 




5 




4 




3 




2 









inch 


oz. 


= 


.1000 


dr. 


= 


.0875 




= 


.0750 




= 


.0625 




= 


.0500 




= 


.0375 




= 


.0250 




= 


.0125 



354 MECHANICS 

The amount of rainfall in any country is a matter 
of great importance to that country, and, like the 
rise of the Nile in Egypt, it indicates the coming 
state of the crops. If we have too small a rainfall, 
drought and withered crops follow, and if we get 
too great a fall of rain, drowned out crops, and dis- 
astrous floods occur, so you see how necessary it 
is that those people who are elected to look after the 
welfare of a nation, should keep posted on matters 
of rainfall in all its phases. In India, China and 
some other parts of the world the question of rain- 
fall is one of life and death to the people, and most 
of the great famines of the past have been due 
to the small rainfall. Hundreds of thousands of 
people used to perish by famine and disease year 
after year. Much of this danger from shortage of 
rain has happily been avoided in India by the efforts 
of the British government, which has inaugurated 
and carried out great schemes of irrigation and 
artificial waterways to prevent the recurrence of 
famine from drought. Our own government also 
is expending large sums of money on irrigation plans 
now being executed in Arizona, Texas, Colorado 
and other states, which will render immense terri- 
tories fit for cultivation, which would otherwise 
have remained barren and of no use. The mattei: 



THE WEATHER AND INDOOR WORK 355 

of rainfall is of the highest importance to a nation 
and to the men and beasts inhabiting it. 

"Will it rain to-day?" is a question frequently 
asked, as regards the weather, showing how impor- 
tant the subject is, and while I am talking on it, it 
may not be amiss to make a few remarks regarding 
the formation and distribution of rain, as formulated 
by learned meteorologists. We are told that the 
two great causes of rain are the sun and the ocean — 
the latter, of course, includes the great lakes and 
rivers — and since these two factors may be taken 
as constant, it follows that the rainfall over the 
earth as a whole will always be constant, while the 
local variations will be due to local conditions. The 
rain which falls on this continent is drawn up by 
the sun from the various sources, but the conditions 
which cause its precipitation may be said to be 
local. To your imagination may be left the tracing 
of the journey of the rain drops back to the ocean 
again. The starting points in considering the causes 
of rain are, therefore, heat and moisture. From 
the surface of land and water moisture is continually 
evaporating into the atmosphere, and the higher 
the temperature of the air the more watery par- 
ticles it can hold. If any reduction in the tempera- 
ture of this saturated air should take place, the 



356 MECHANICS 

vapour becomes visible as fog, mist, or cloud, and 
it is from this vapour that the rain drops are formed. 
Recent research says that these watery particles 
require minute dust atoms as nuclei before they 
can form, and it has been estimated, by experiment, 
that there are one thousand millions of them in a 
cubic foot of saturated air, though their total weight 
amounts to only 3 grains. Accepting these figures, 
the mathematically inclined may be told that it 
would require a cloud three miles thick to produce 
one inch of rainfall. But before these watery par- 
ticles can fall to the earth as rain, they must first 
form into rain drops, and the question arises, how 
are rain drops formed? 

These watery particles pass into the air by evapo- 
ration, and there are several ways by which the 
reduction in temperature necessary to render them 
visible can be brought about. It may take place 
through contact with a colder body of air, by ex- 
pansion, or by a reduction of pressure owing to a 
rise in altitude. Clouds are said to be formed by 
this last method, for a volume of hot air rises 
higher and higher until it presently reaches a 
point when its contained vapour condenses, and be- 
comes visible as a cloud. Meteorologists repeat 
one of these processes in the laboratory, by releasing 



THE WEATHER AND INDOOR WORK 357 

from pressure damp air placed in a convenient glass 
globe, and are able to see something of the methods 
of cloud formation. It has been customary to speak 
of a cloud as being composed of watery particles 
floating motionless in the upper air; but although 
it may appear unchanged in form, it is all movement. 
So soon as ever a cloud is formed, its particles of 
moisture commence to fall slowly, the rate of fall 
being in proportion to the diameter of the particles, 
and this is due to the slight resistance the air makes 
to such very small atoms. In passing, it may be said 
that one observer estimates the diameter of these 
particles as from .00033 inch to .00025 inch. The 
component parts of a cloud are always in motion 
and recognizing this fact it becomes possible to 
take the first step in considering the formation of 
a raindrop. 

An easy way out of the difficulty of explaining the 
formation of a raindrop, is to say that, since clouds 
are so often of two opposite electric potentials, there 
is always a continuous bombardment of watery 
particles taking place, and some of these must unite 
and fall as rain. The meteorologist is always 
tempted to call in electricity as an agency whenever 
he is anxious to discover a cause for some partic- 
ular phenomenon. This often explains one mystery 



358 MECHANICS 

by another. The production of rain, snow, and hail 
has for many years been explained by vaguely 
ascribing them to the action of electricity, without 
any information being forthcoming as to the pre- 
cise way in which this action takes place. Meteor- 
ologists are at present attempting to find a more 
satisfactory explanation. Another theory is that 
the particles of moisture in a cloud, like all other 
objects, radiate heat, and, growing cold, condense 
moisture upon their surfaces, thereby increasing 
in weight until they assume the proportions of a 
drop. This seemed a reasonable explanation of the 
formation of a rain drop until modern research de- 
cided that whenever moisture is condensed, latent 
heat is set free, so that all moisture deposited on a 
watery particle only serves to raise its temperature, 
and cause evaporation of the moisture thus acquired. 
The particles of water could not by this means grow 
to the full estate of a rain drop, and the theory is 
being gradually abandoned. 

A rain drop is, according to modern meteorolo- 
gists, explained in a very simple way. It has been 
seen how the hot, damp air is formed into a cloud, 
and also how the minute particles of water at once 
commence to fall slightly earthwards. Now these 
little particles as they pass into a warm layer of air 



THE WEATHER AND INDOOR WORK 359 

would soon be evaporated, and would never reach 
the earth at all. Their downward journey, however, 
is often through a cloud many miles thick, and the 
most modem and simple theory is that in this jour- 
ney they overtake some of their fellows, and the 
joined particles increase their rate of travel, overtake 
more and more particles until they presently become 
heavy enough to take the final plunge to earth. 
Were it possible to be just beneath a cloud, an ob- 
server would see rain drops coming from it of all 
sizes. The same process goes on in drops, which 
trickle down a window pane, or in the effervescing 
globules in a bottle of seltzer water. In the latter 
instance, the process is reversed, for the globules 
are seen overtaking one another in an upward 
direction. There are many points in favour of this 
theory of the formation of rain drops, and at least 
it gets rid of those elaborate complications, elec- 
tricity and condensation. With respect to the 
formation of rain by the impinging of clouds upon 
the tops of cold mountains in the northwest, one 
authority argues that moisture is in these circum- 
stances not condensed solely because of the con- 
tact with the cold hills; that rain there is due to a 
mechanical cause, the watery particles being 
squeezed together by the grinding eflPect of the 



360 MECHANICS 

clouds on the sides of the mountains in such a way 
that they coalesce, and fall as drops. 

A rain drop's roundness is due to the action of 
capillarity. Just as a circle made by dropping a 
stone into water owes its shape to the fact that the 
force is able to act equally in all directions, so a 
rain drop is spherical, owing to similar untram- 
melled action on the part of capillarity. These are 
some of the explanations of the formation of a rain 
drop, but meteorologists still have the subject under 
consideration. 

The periods of rainfall are divided broadly into 
times of drought and times of flood, and it is in 
these matters that meteorology is seen in its practi- 
cal aspect. Some people ask, ''Where does all the 
rain come from?" Others are surprised that rain- 
fall totals up to such large quantities. 

A fall of rain to a depth of one inch over a very 
limited area, represents millions of gallons, but in 
spite of this vast quantity of falling water, many 
times multiplied if the annual rainfall be taken 
into ac.count, there still are water famines. The 
question has often been debated whether man can 
modify climate or effectively tamper with the proc- 
esses which produce rain. Rain making has not, so 
far, been a success, though the firing oflf of heavy 



THE WEATHER AND INDOOR WORK 361 

guns has been tried, along with the legitimate avo- 
cations of the meteorologist. The afforesting or 
deforesting of a district has, however, a marked 
effect upon rainfall. Three notable instances are 
Ascension Island, Malta, and the neighbourhood of 
the Suez Canal, where the planting of trees seems 
to have had the result of increasing the rainfall. 
The effect of trees is felt more in the storage of 
rain water, while leaves and roots serve to retain 
moisture that would otherwise quickly drain away. 
A hill may be converted into a sponge by the 
judicious planting of trees. The question of the 
storage of rain water becomes more pressing each 
year, and the longer the settlement is put off, the 
more difficult will decision become. Engineers called 
upon to prevent floods and to conserve rain water 
reply, "Save our forests, cover the land with 
trees. " 

The fact that such problems arise, serve to show 
how great is the amount of water formed by the 
continual falling of the tiny rain drops. As long 
as this beneficent downpouring is allowed to drain 
away unused or uncontrolled, so long will droughts 
annoy and water famines bring distress. 

In recording weather conditions, symbols are 
sometimes used in order to shorten reports and, 



362 MECHANICS 

while not universal, most nations adopt these: 
The symbol for rain is o, a small circle filled in; for 
lightning q^; for thunder T, while the two latter 
combined make Tq^, the symbol for a thunder-storm. 
Nearly every weather component has a distinctive 
symbol, and since a great part of the meteorologist's 
work consists in going over records of observations 
to search for the number of times the diflFerent 
phenomena occur during each week or month, the 
task is much simplified when observers employ the 
symbols, as it is easier to pick out a symbol from a 
printed or written page than it is to recognize a 
word. These symbols, moreover, have been agreed 
upon as a sort of international notation, and make it 
easier for the meteorologists of different countries 
to understand the records of foreign meteorological 
services. 

Everybody does not know the Russian word for 
snow, or the Dutch for hail, or the Bosnian for rain, 
but all who run, may read when *'snow" is uni- 
versally written, and hail represented by a wedge- 
shaped figure with lines drawn across. Time and 
space being limited, nearly all published records of 
weather merely set forth the number of days through- 
out the year on which the difiFerent phenomena 
occurred, and should snow, hail or thunder happen 



THE WEATHER AND INDOOR WORK 363 

two or three times in one day, it would still be 
counted only as one day. The yearly totals, there- 
fore, show the number of days on which these con- 
ditions have been observed. It is now an almost 
universal custom to count .01 inches or more during 
the twenty-four hours as a day of rain. Accord- 
ingly, where observers read their rain-gauge to three 
places of decimals, that on which less than .005 inch 
fell would not be counted as a rainy day. Smaller 
amounts would, however, be included in the total. 
Dew may sometimes fall to the amount of .01 in. or 
more; and that is counted as a rainy day, the rule 
being to consider the amount of precipitation, 
irrespective of the manner in which it has fallen. 
If you wish to make these observations comparable 
with published records you would do well to conform 
to these rules. 

HAIL 

Hail, the next weather component to be con- 
sidered, presents many difficulties when the attempt 
is made to explain its origin and formation. Those 
who have anything to do with scientific matters 
are well acquainted with the hypothesis, which ex- 
plains a given fact, and in considering the subject 
of hail, the meteorologist hears of many hypotheses 



364 MECHANICS 

which are put forward as complete explanations 
of this phenomenon. Caution is, therefore, to be 
exercised and every reported statement severely- 
questioned. Remembering the aphorism: "The 
man or boy who never makes a mistake will never 
make anything," meteorologists have attacked the 
question of hail formation, and, although many mis- 
takes have probably been made, the subject has 
lost a good deal of its mystery. For many years, it 
was customary to be content with a recognition of 
the fact that hail and lightning very often occur 
together, and the conclusion was drawn that the 
one was in some way responsible for the other. SufB- 
cient corroboration of this hypothesis was to some 
meteorologists, found in the fact that thunder and 
lightning are said to be almost unknown in the 
Arctic regions, and this supposed companion, hail, 
almost unknown. Roughly speaking, the assump- 
tion was that lightning, as it flashed through a cloud 
laden with watery particles, caused hail to form. 
Such an explanation only tended to make the subject 
more mysterious, and the question. How is hail 
formed? practically remained unanswered. Many 
simpler explanations of hail have been propounded 
as the result of modern research, and, like rain and 
lightning, it has been demonstrated that hail owes 



THE WEATHER AND INDOOR WORK 365 

its origin to the movement of the minute watery 
particles found everywhere in the atmosphere. 

The clouds from which hail fall are ordinarily 
of great height above the earth, 40,000 feet or even 
higher. These are the well-known cirrus. The first 
condition necessary to the formation of hail is a 
powerful ascending current of hot, moist air, which 
may condense its moisture in the shape of the large 
woolly cloud, known as cumulus. Such a cloud 
may be 100 cubic miles in volume, and as long as 
it retains its shape nothing is likely to fall from it 
to the earth beneath. Before the formation of a 
thunder-shower, cirriform fibres in some instances 
break away from the upper portion of this cloud, the 
electrical tension is lowered, and rain falls. The 
coalescing of the particles of moisture has a great 
deal to do with the changes which take place in a 
cloud. All these changes take place in the higher 
clouds in a marked degree, and the varying strata 
through which the watery particles pass in ascend- 
ing to and decending from this great height bring 
about the violent change essential to the formation 
of hail. The necessary conditions for hail are, there- 
fore, a powerful, hot, ascending current of air and 
great variation in the strata of the atmosphere as 
regards moisture and temperature. Mountains as- 



366 MECHANICS 

sist in forcing currents of air upwards, and one mass 
of air impinging on another is also thrown upwards, 
so that condensation of moisture rapidly takes place. 
A hail cloud may be described as a tower of hot air, 
from the top of which, vapor is ejected into a frosty 
region. Hot plains are accordingly the most favour- 
able spots for the formation of hail, and in moun- 
tainous districts, more hail falls at a distance from 
the mountains than among them. Snow is observed 
in all latitudes and at all heights, but hail is con- 
fined to middle latitudes, and is rare in high latitudes. 
The places most affected by hail are those in which, 
the temperature and humidity of the air are high, 
while above, at a great height, there is a cold area 
below the temperature of freezing point; but, as 
in the case of the rain drop, before anything can be 
definitely stated, it must be shown how the par- 
ticles of moisture coalesce to form hail. 

SNOW 

Snow is frozen water which falls instead of rain 
when the temperature is below the freezing point. 
The ultimate constituents of snow are tiny, six- 
pointed crystals of ice. They assume in combina- 
tion a thousand different figures (Fig. 210), all ex- 
ceedingly beautiful. Professor Tyndall has shown, 



THE WEATHER AND INDOOR WORK 367 

further, that the ultimate particles of ice are also 
these six-pointed stars. The white colour of snow is 
caused by the comming- 
ling of rays of all the 
prismatic colours from the 
niinute snow crystals. 
Separately the crystals 
exhibit different colours. 

Snow is usually from 
ten to twelve times as 
light as water, bulk for 
bulk; so that where the 
snow falls pretty evenly, 
the corresponding rain- 
fall is readily determined 
by merely measuring the 
depth of snow and taking one tenth of the result. 
The more accurate plan, however, is to thrust 
the open end of a cylindrical vessel into the snow, 
invert the cylinder, and then melt the snow in it. 

Snow plays an important part in the economy of 
nature. In the first place, the mere transformation 
of the water particles into ice is a process during 
which a large amount of heat is given out ; so that 
we may regard the formation of snow renders the 
air currents warmer than they would otherwise be. 




Fig. 210. Snow crystals 



368 MECHANICS 

Fallen snow serves to protect the ground, for, owing 
to its loose texture, it is a bad conductor of heat; so 
that, while checking the radiation of heat from the 
earth into space, it does not draw off the earth's 
heat by conduction. The ground is thus often 23 
degrees to 30 degrees warmer than the surface of 
the snow above, and sometimes the difference of 
temperature has been more than 40 degrees. 

Red snow and green snow have been met with, 
more commonly in Arctic regions, but also in other 
parts of the world. These colours are caused by the 
presence of minute organisms — a species of alga 
called Protococcus nivalis. 

The snow line of mountains is on the slopes below 
which, all the snow which falls in the year, melts 
during the summer. Above the snow line, therefore, 
lies the region of perpetual snow. The altitude of 
the snow line depends on a variety of conditions. 
The latitude of a snow range is, of course, important 
in determining the position of the snow line, but 
many other circumstances have to be considered, as 
the shape and slope of the mountain, the aspect of 
either side of the range, the character of the sur- 
rounding country, the prevalent winds, and so 
on. 

The following table shows the observed height of 



THE WEATHER AND INDOOR WORK 

the snow line in feet above the sea level in different 
places: 



Place 


Latitude 


Height 


Place 


Latitude 


Heigh 


Spitzbergen 


. 78 


N, 


0. 


South Himalaya . 


28 


N 


15.500 


Sulitelma, Sweden 67 


5' 


3.835. 


Abyssinian Mts. 


13 




14.065 


Kamtchatka 


. 69 


30 


5.240 


Purace . 


2 


2' 


15.381 


Unalaschta 


. 56 


30 


3.510 


Nevades of Quito 







15.820 


Altai 


. . 50 




7.934 


Arequipa, Bolivia 


. 16 


s 


17.717 


Alps . . 


. 46 




8.885 


Paachata, Bolivia 


18 




12.079 


Caucasus 


. 43 




11.063 


Portillo, Chili . 


. 33 




14.713 


Pyrenees 


. 42 


45 


8.950 


Cordilleras, Chili 


. 42 


30 


6.010 


Rocky Moun 


tains 43 




12.467 


Magellan Strait 


. 53 


30 


3.707 


North Himal 


aya 29 




19.560 











DESIGNING, MAKING, AND INFLATING PAPER 
BALLOONS 

Draw a rough figure of the balloon, as shown at 
A, (Fig. 211.) 

Divide this into any number of parts (the more the 
better) by horizontal lines. Take a radius of 
balloon on each line, and describe circles, B. 

Divide this into twelve parts by radius lines, then 
make pattern as follows: Draw a perpendicular, C, 
with horizontal lines at distance of horizontal lines 
on A, but measured on circumference as c d. Then 
set oflf on each line from perpendicular one half the 
distance between the radius lines, B, on the cor- 
responding circle as e f; draw line through points 
thus found, and result will be shape of each section. 
Allow a little on one side when cutting out for past- 



370 



MECHANICS 



ing. This will be best made with strong tissue 
paper of any colour desired. 

Another method, giving a shape somewhat diflFer- 

ent, is shown in 
Fig. 212. First 
draw an elevation 
of the balloon it is 
intended to make, 
either full size, on 
the floor, or to scale. 
The shape here il- 
lustrated differs 
slightly from that 
of balloons usually 
sold ready made, 
being wider at the 
mouth. This shape, 
however, is not so liable to catch fire when swayed 
about by the wind. Divide the elevation into any 
number of parts (the more the better) by horizontal 
lines as shown (No. 1). Take the radius of the 
balloon on each line, as A B, describe circles (No. 2,) 
and divide these into twelve parts by radial lines. 
Then to make a pattern, draw a perpendicular (No. 
3), with horizontal lines at the distance of the hori- 
zontal lines (No. 1,) but measured on the circum- 




Fig. 211 



THE WEATHER AND INDOOR WORK 371 

ference as C D. Then set off on each line from the 
perpendicular half the distance between the radius 
lines (No. 2), on the corresponding circle as E F, and 




Fig. 212. An improved balloon 

draw a line through the points thus found, and the 
result will be the shape of each section. Allow a 



372 MECHANICS 

little (say 34 inch), on one side when cutting out for 
pasting. Each section will be made up of one, two, 
or three pieces, according to the size of the balloon 
to be made. If the pieces are cut as shown (No. 
4,) a great saving of paper results. To paste these 
pieces together, place them in a pile on the table or 
bench with the edges flush and a piece of waste paper 
under the pile. Now rub the top sheet with the 
thumb nail until each piece is moved back from the 
one immediately under it about one-fourth inch. 
Place a piece of waste paper about the same dis- 
tance from the edge of the top sheet, and pass the 
paste brush over the whole of the exposed edges. 
No. 5 will explain what is meant. Now place two of 
the completed sections together so as to look like No. 
3, with a small part projecting as shown by the dotted 
line G. Paste the edge of the under section — that 
is, the part hatched — and turn it over on to the 
dotted line H. When each two of the sections have 
been joined in this way, proceed in the same manner 
to join these together till the whole is completed. 
A circular piece of paper is cut out to join the sec- 
tions at the top, and a loop of string should be pasted 
to the top to suspend the balloon while inflating. 
A ring of wire with two cross pieces is fitted to the 
bottom of the balloon, and the inflammable material, 



THE WEATHER AND INDOOR WORK 373 

— tow soaked in methylated spirits — is fastened 
to the junction of the cross pieces. 

MAGNETIZED WATCHES 

The owner of a good American watch was a little 
troubled concerning it, because it had been running 
irregularly for some time past. It came out that 
he had visited the electric power house and had 
stayed for some time examining the works and 
machinery, so that parts of his watch had evidently 
become magnetized by the influence of the dynamos. 
The watch had been made some time ago, and had 
not the power to resist, or neutralize electric in- 
fluences, that most watches have now. 

To demagnetize the watch would bring it back to 
its original condition, but a second visit to the 
lighting plant would again spoil its time-keeping 
qualities. The watchmakers now have a way of 
making watches so that they are not affected by 
magnetism, but comparatively few of the time pieces 
in use are non-magnetic, and the average watch is 
subject to these seasons of fickleness. 

The exceedingly fine and exact construction of 
the watch is not realized by the average possessor 
of the article. An examination of the works of a 
watch shows the mechanism as now constructed, 



374 MECHANICS 

although very small in size, to be accurately planned 
and executed. Changes of temperature are pro-' 
vided for, so that the movement is automatically 
adjusted. The mainspring and train of gears are 
usually concealed, while the balance and hair springs 
are in full view when the case is open. Upon the 
regularity of the movement of the balance depends 
the time keeping quality of the watch. On looking 
closely at the balance, you will observe that it is 
not a complete ring, but two halves supported at 
one end. These rings bear a number of large- 
headed screws, placed at irregular distances, which 
give it the exact weight and balance required. These 
half rings will also be found, on looking closely, to 
be composed of two metals so closely joined that a 
difference in colour alone gives evidence of the quality. 
This arrangement of iron and brass, on account of 
their different coefficients of expansion and con- 
traction with changes of temperature, has been so 
carefully constructed that, with changes of tempera- 
ture, the balance assumes such forms as to give it 
a uniform rate of motion. 

The parts affected by magnetism are the balance 
and springs. The balance in an ordinary watch 
moves five times a second, 18,000 times an hour, and 
432,000 times each day; but a slight change in the 



THE WEATHER AND INDOOR WORK 375 

forces that move it is necessary to make a difference 
of several minutes each day. As the balance moves 
back and forth, the magnetism of the mainspring is 
pulling or pushing it. If this force were constant, 
and always in the same direction, the watch would 
run uniformly. Such, however, is not the case. 
When the mainspring is tightly wound, its magnetic 
poles are in a certain direction, and in unwinding 
they are constantly changing, so that the direction 
of this force is also constantly changed. The effect 
on the balance is to cause the watch to run too fast 
sometimes, and too slow at other times. 

Non-magnetic watches are made with these parts 
of a non-magnetic metal, so that they are not in- 
fluenced by electric machinery. For testing watches 
a small compass is used. When placed over the 
balance, the needle will vibrate with the motion of 
the balance in proportion to its magnetism. 

A boy's wheel-barrow 

The bottom, sides, and ends were about three- 
quarters of an inch thick. Good white and red pine 
were used for the purpose. The stiles and rails of the 
bottom framework were mortised and tenoned togeth- 
er as shown at Fig. 213; these may be just stubbed 
together, or the tenons of the rails can go right 



376 MECHANICS 

through the stiles. The most satisfactory job is to 
groove the sides and ends together, and put all to- 
gether with oil paint in the joints. If the joints are 
painted before the framework of the barrow is put 
together, it will last for years; otherwise, being a 




Fig. 213. A boy's wheel-barrow. Perspective view 




213 A, Boy*s wheel-barrow. Side elevation 



THE WEATHER AND INDOOR WORK 377 

boy's wheel-barrow, it would likely often be forgotten 
and left out in the rain, and the joints getting wet 
would hasten decay. Two coats of good oil paint. 




213 B. Finished plan 




213 C. Plan of frame 

Indian red, will give it a very nice appearance. 
This barrow, while not intended for heavy work, is 
capable of carrying quite a load. The wheel was cut 
out of a piece of plank about 13^ inches thick, hooped 



378 MECHANICS 

up with an iron tire made from heavy hoop iron. The 
axle was made of wood with a %-inch round iron rod 
running lengthwise through it and projecting about 
three inches through on each end. The arbours or 
boxing, in which ran the ends of the round rod, were 
formed on the ends of the handle stiles, as may be 
seen in the illustration. The cost of all the 
materials for this really useful article was less than 
$1.50, all told. 

VACUUM CLEANERS 

A single hand vacuum cleaner can be made from a 
powerful suction pump, as indicated in the sketch 
Fig. 214. This should be connected with a metallic 
box by means of a flexible armoured rubber hose, 
covered at the end with a piece of fine wire gauze 
to prevent large particles of dust, etc., being drawn 
into the pump. To another opening of the box 
should be fastened another flexible rubber tube, with 
a bell-shaped metal attachment at the end. The 
bell-shaped arrangement should be held closely to 
the carpet while the pump is in action. Within the 
box, the pipe to which the pump is. attached should 
be bent upward, so that the rush of air shall not 
bring the dust with it; the object being to collect the 
dust in the box. A lid covers the box so that it can 



THE WEATHER AND INDOOR WORK 



379 



be emptied from time to time. The success of this 

arrangement depends on the strength of the pump; 

if it be a weak one, 

the inrush of air 

through the funnel 

will be so slight that 

the dust will not be 

raised. 

Rotary pumps are 
not satisfactory for 
vacuum cleaners. 




Fig. 214. Home-made vacuum cleaner 



The best type for this work is a plunger, having a 
large displacement, with a comparatively short 
stroke in proportion to the diameter. A suit- 
able pump is shown in 
the accompanying illus- 
trations. Fig. 214, shows 
the section of a single 
barrel, but should a great- 
er supply be required, two 
barrels may be worked 
and connected as shown 
in Fig. 216. The pump 
is easily made, and of 
light construction. In Fig. 215, is a brass cylinder 
with a flange at the bottom; this may be made out 




Fig. 215. Metallic vacuum cleaner 



380 MECHANICS 

of a length of 3-inch brass tube with a flange cut 
from 3^ -inch sheet brass. The barrel is 8 inches long. 
G is the plunger, which may be constructed as a 
piston; but in the drawing, it is adapted to the 
arrangement that is shown in Fig. 216. With a 
piston will be required a guide for the rod at the top 
of the cylinder. E is a hydraulic cup, its leather kept 
soft and pliable by oiling. B is the base, which is 
hollow, and may be built up in sheet metal. At the 

centre at J, the base 
is divided into two com- 
partments, one side 
being the inlet to the 
pump from the dust 
box, and the other 
in communication 

Fig. 216. Simple vacuum cleaner ^j^j^ ^j^^ ^^^j^^ ^^j^^ 

C. C and D are two valves with guards. The 
valves are discs of very soft and pliable leather, 
well saturated with grease, D being the inlet from 
the dust box, and C the outlet to the atmosphere. 
The drawing clearly shows the construction of the 
other parts. Fig. 216 shows two pumps fitted to 
one base and worked by a rocking lever; both pumps 
are in communication with the one inlet N. This 
arrangement of pumps is easy to work, portable. 




THE WEATHER AND INDOOR WORK 381 

and well adapted to domestic purposes in cleaning 
carpets. 

Fig. 217, which is reproduced from The Scientific 
American, exhibits an ingenious form of vacuum 
cleaner. It has recently been patented, and con- 
sists of a suction-fan operated by a water-motor 
that may be attached to the ordinary kitchen faucet. 
A tube is connected with the chamber of the suction- 
fan, and this terminates in a suitable nozzle, or 
foot plate, which 
may be moved over 
a carpet or rug to 
draw out the dust 
and dirt. One of 
the advantages of 
this system is that 
dirt drawn up by 
the suction fan can 
be carried away with the water down the kitchen 
drain. 

A good power-driven cleaner may be made at 
home, says Popular Mechanics, by following these 
directions: First take a good pine board, s 1 inch 
thick, 1 foot wide, and 3 feet long, and nail to each 
end a 1-foot length of 2-inch by 2-inch pine, as 
shown at A, Fig. 218. Next a ^^-inch board, 1 foot 




Fig. 217. A motor vacuum cleaner 



382 MECHANICS 

wide and about 1 foot, 3 inches long, should be 
fastened near the centre, and at right angles to the 
first board, as shown at B. Procure a tin pan meas- 
uring about 10 inches in diameter and 3 inches deep. 




Fig. 218. Home-made power-driven vacuum cleaner 

This pan shown at C, must be fitted with two valves, 
which are the most important and difficult part of 
the work. Cut, from a smooth piece of pine, 1 inch 
thick, two discs, 5 inches in diameter, with a 3-inch 
Jiole in the centre of each. Obtain a sheet of pack- 
ing rubber, 3^ of an inch thick, and cut from it two 
discs, each 5 inches in diameter, and two 3J^ inches 
in diameter. One of the discs of wood should be 
fastened to the back of the pan at the top, as shown 
atD, Fig.219, with one of the 5-inch diameter rubber 
discs placed between the tin and the wood, and both 
secured to the tin by a row of small bolts around the 
outside edge of the wood. A hole, 3 inches in diam- 
eter, can now be cut through the tin and rubber, 
using the hole in the wood as a guide. Two discs 
with a diameter of 334 inches should be cut from cigar 



THE WEATHER AND mDOOR WORK 

box wood and fastened centrally on the Sj^-inch 

rubber disc. One of 

the latter pieces 

should be fastened 

by its top edge to 

the top edge of the 

5-inch disc of wood, 

as shown in E. This 

forms a flap valve, 

taken to see 





ai^^m^m 


..bS^ 


B^^^'^iP^^^Sk^^^^^^'I'l 


H 


el 


^^1^ W 


F 


*^ H 


ij 1 ^^S^p^ 1 u 


s 


> JisM 


IV /f^^^ /i 


K^ 


% ^ 


r' 


^^Mi 


n. 


Ji jJ* 











Fig. 219. 



Home-made, power-driven 
vacuum cleaner 



and great care should be 
that the rubber disc covers the 
opening all the way around when the valve is closed, 
so that it will be air-tight. A spring w^ill 
be necessary to quicken the action of this valve. 
This is best made by fastening a narrow strip of 
wood across the valve opening on the inside of 
the pan, as shown at F, and attaching a rubber 
band to the centre of the valve and to this stick. 
This completes the outlet or exhaust valve. An- 
other valve must now be made in the same 
manner, and fastened to the bottom of the pan 
on the inside, as shown. This is the inlet valve, 
and works in the opposite direction to the outlet 
valve just described. 

Next procure a piece of leatherette about twelve 
inches in diameter, or large enough to cover the 
opening of the pan. This is to be used for the dia- 



884 MECHANICS 

phragm. Cut a round hole about 8 inches in 
diameter in the upright piece B (Fig. 218), its centre 
about 7 inches from the top. From a piece of 
3^-inch pine, cut two discs 6 inches in diameter. 
Also secure a piece of hardwood H 1 inch by 1 foot 
2 inches. The discs G should now be placed, one on 
each side of the leather diaphragm, exactly in the 
centre, and fastened to one end of the 1-foot 2-inch 
piece by means of a long screw. This piece H 
should exactly be in the centre of the diaphragm. 

The pan can now be put in place. Set the dia- 
phragm over the hole in the board B, the stick pro- 
jecting through the hole. The pan is now placed 
over the diaphragm, and held by means of small 
bolts around the edge. The diaphragm between the 
wood and the tin acts as a gasket, and makes an 
air-tight joint. 

Secure an air-tight tin about 8 inches in diam- 
eter and 12 inches high, and fasten it to the 
base board, as shown at J, Fig. 218. The cover of a 
coffee tin should now be soldered over the inlet 
valve, as shown at K, Fig. 219. Solder a hose connec- 
tion in the centre of this cover, also one in the side of 
the tin, as shown at L, Fig. 218. Couple a short 
piece of hose M to these connections. The strainer 
S should be made of very strong and closely woven 



THE WEATHER AND INDOOR WORK S85 

unbleached drill. Make it in the form of bag with a 
1-inch hem at the top, and place it in the tin, as 
shown by the dotted line, the hem fitting closely 
over the inside edge of the tin. The cover of the 
tin is made from a flat pine board about one inch 
thick, and is held in place by two 3^ -inch rods 
fastened in the base board. These rods have thumb 
nuts on the top, which allow the cover to be readily 
removed or tightened down. It is best to place a 
rubber or leather gasket between the cover and the 
edge of the tin so as to make an air-tight joint. 

An air-tight piece of garden hose can be used for 
the suction hose N, one end being fastened in the 
centre of the cover and the other to the brush or 
nozzle R, Fig. 218. It is best to buy this nozzle, as 
it would be rather expensive and unsatisfactory if 
home-made. 

This machine may be driven by an electric motor of 
about l}/i horse-power, which should be placed in the 
position shown in Fig. 218. The end of the connecting 
rod H is fastened to a crank on the motor shaft, 
and allowed to have about a one and one half inch 
stroke. The motor is wired up with a switch, P, and 
it would be best to connect to a rheostat, to allow the 
regulation of speed best suited to the machine. This 
can readily be determined after the machine is 



386 MECHANICS 

started. If an electric motor is not available, a 
small water motor will do equally well ; or it may even 
be run by hand, by means of a long lever, fulcrumed 
at P. 

The machine is now ready for using. First, 
however, test it all over for leakage, as its success 
depends on its being perfectly air-tight. As the motor 
revolves, the rod H is drawn forward, bringing with 
it the diaphragm. This creates a partial vacuum 
in the pan C, which opens the inlet valve, sucking 
the air through the suction hose and strainer, the 
air carrying with it the dust and dirt. The refuse 
is left in the strainer bag while the air goes on through 
the connecting hose and pan and outlet valve into 
the atmosphere. After the article being cleaned 
has been gone over thoroughly, care being taken to 
hold the nozzle against the material, the cover may 
be removed and the bag emptied. 



IV 

MOTORS AND TYPE-WRITERS 

MOTORS, GASOLENE AND STEAM — AUTOMOBILE FRAMES 

— THE MODERN TYPE-WRITER — DIRECTIONS 

FOR SECURING COPYRIGHTS. 

THERE are two classes of heat engines 
in use; in one class the combustion 
takes place on the inside of the cylinder 
or generator, just as j&re is applied to a tea- 
kettle, and the heat is transmitted by conduc- 
tion through the metal walls to the part of ma- 
chine doing the work. Motors and machines of 
this kind, are generally called "external com- 
bustion" engines, of which the steam engine is a 
prominent example. 

Engines where the combustion takes place inside 
the machine itself, and acts directly on it, are en- 
gines of the second class, termed "internal com- 
bustion engines." The gasolene engine is of this 
type, and so are all gas and oil engines. 

The principle of the motor-cycle engine, in its 
action, is similar to the regular automobile engine 

387 



388 MECHANICS 

and the gas engine. All these are internal combus- 
tion or explosion engines; that is, their motive power 
is derived from the force exerted by the explosion 
of a gas while under compression, the compressed 
gas generally ignited by means of an electric spark. 
In the case of gasolene motors, the gas is obtained 
from the liquid gasolene, either by allowing air to 
be drawn through it or by spraying the spirit through 
a small hole, the latter being the method most 
generally used. A great quantity of air has to be 
mixed with the vapour before it will ignite. The 
amount that is required varies considerably, at- 
mospheric conditions and the height above sea 
level causing variations in the demand. The action 
of the common gasolene engine is known as the 
"four-stroke-cycle," that is, there are four strokes 
of the piston for every impulse, one being a ''power" 
stroke and the other three "duty" strokes, as it 
were. Each performs a certain operation that is 
necessary for the correct working of the engine. 
Some engines are worked on the "two-stroke-cycle" 
principle; in this case, there are only two strokes 
for each impulse. This type of engine has many 
disadvantages, and there are very few two-stroke 
engines in use for driving motor cycles. 

The principle of the "four-stroke-cycle" is shown 



MOTORS AND TYPE- WRITERS 389 

in Figs. 220 to 223. In Fig. 220 the piston A is just 
beginning the downward stroke, and the valve B is 
opened by the pressure of the atmosphere, or by 
mechanical means. The piston in descending causes 
a partial vacuum in the cylinder head or top C, 
which allows the atmospheric pressure on the sur- 




Fig. 220. Suction stroke begun Fig. 221. Compression stroke begun 

face of the gasolene in the carburetor to force some 
of the liquid through the spray hole, thence through 
the inlet-valve opening D, into the compression 
space of the engine cylinder. The suction of the 
piston does not bring in the explosive mixture of gas 
and air; it is the pressure of the atmosphere that 
causes the mixture of gas and air to rush into the 
cylinder. Just before the piston is at the extreme 



S90 MECHANICS 

end of the downward or outward stroke, the inlet 
valve B is closed by the spring shown, and the piston 
begins the first upward or "compression" stroke 





Fig. 222. Power stroke begun Fig. 223. Exhaust stroke begun 

with both the inlet valve B and the exhaust valve 
E closed. The charge is being compressed when 
the piston is on its upward stroke, as shown in Fig. 
221. Speaking generally, soon after the piston is 
over what is known as the "dead centre," and is 
about the position shown in Fig. 222, an electric 
spark is made to jump across two points of the 
sparking plug F; this ignites the mixture of gas and 
air (which is at a pressure of about 80 lb. per sq. in.), 
and the explosion causes the piston to descend on the 
power stroke. Just before the piston reaches the 



MOTORS AND TYPE -WRITERS 391 

bottom of the power stroke, the exhaust valve E, 
Fig. 223, opens, and remains open during the upward 
stroke. The momentum of the fly-wheels, etc., 
carries the piston upward, and thus forces out the 
burnt gases through the exhaust opening G, and 
from there to the silencer. Immediately the piston 
begins its next downward stroke, the inlet valve 
opens, fresh air is drawn in, and the cycle of oper- 
ations is repeated as before. The illustrations 
show a magneto gear driven by the engine. 

These engines when properly arranged are made to 
do service as marine motors, and are then installed 
either horizontally or vertically. A vertical engine 
has been shown on previous pages, but perhaps a 
little further explanation may not be amiss. En- 
gines for boats are made with one cylinder or with 
more, and there are many considerations which 
make an engine of two or more cylinders particularly 
desirable. It is a self-evident fact that when the 
limit of size of a single-cylinder is reached, it is 
necessary to add other cylinders if greater power 
is desired. Even for moderate or small powers, 
there are many advantages. Among these may be 
noted the fact that with the proper arrangement of 
cylinders the impulses may be made to occur at 
shorter intervals than with a single-cylinder engine. 



392 MECHANICS 

Thus with a two-cylinder engine, the cylinder may 
be so arranged that the impulses will occur twice 
for every revolution instead of once, as in a single- 
cylinder. This gives a more even turning effect 
to the shaft, and consequently steadier running, 
and it also requires a less heavy fly-wheel. The 
vibration is much less, as one set of working parts 
may be made to travel upward while the other is 
travelling downward, thus neutralizing the throw 
of each and lessening the vibration. 

In case of the disablement of one cylinder, there 
is the chance of getting home on the remaining ones. 
The weight, power for power, of the multiple- 
cylinder engine is less than that of the single- 
cylinder engine, as the weight of the fly-wheel and 
other working parts is less. 

While for marine work, single-cylinder engines 
have been built as large as eight or ten horse-power, 
they are so large as to be rather cumbersome and 
the practice now is to build engines of more than 
six horse-power with two or more cylinders. There 
are several firms who are making double-cylinder 
engines as small as four horse-power, which both 
as to weight and reliability are much superior to 
those of a single-cylinder. 

The original method of constructing a multiple 



MOTORS AND TYPE -WRITERS 

engine, and one which is still used by some builders, 
is simply to use two or more single-cylinder engines 
coupled together. This is a cumbersome method 
and takes up a great amount of space. The sim- 
plest method which can be recommended is that 
shown in Fig. 224. It consists of two single-cylinders 
mounted on a common base of special design, bring- 
ing the cylinders much nearer together than when 
a coupling is fitted to 
connect two separate 
engines — as the 
shaft can be made in 
one piece. This 
particular engine is 
of the two port 
type, two vaporizers 
V-V being used. 
The gasolene enters 
at G and branches 
to each vaporizer. 
The pump is shown at P with the discharge at 
W, piped with a branch to each cylinder. The 
cooling water outlet is at O. The exhausts are 
connected to a common pipe with the outlet at E. 
The igniting gear for each cylinder is independent 
and on opposite ends. By means of the lever L, 




Fig. 224. Two-cylinder engine 



394 



MECHANICS 



which is connected to both igniting gears, the 
time of ignition is regulated and kept the same on 
both cylinders. This allows multiple-cylinder en- 
gines to be built with very few extra parts, as the 
cylinders, ignition gear, etc., are the same as in 
the single-cylinder engine. 

A view of a representative single-cylinder engine 
is shown at Fig. 225. The cam shaft is located at a 
and is driven by the gears which are shown just in 
the rear of the fly-wheel. At c are the cam and the 




Fig. 225. Single-cylinder engine 

roller, which actuates the exhaust valve. The 
cam consists of a collar with a flat projection or 



MOTORS AND TYPE -WRITERS 395 

toe upon its surface; the roller rests just above the 
surface of the collar, and is forced upward when 
struck by the projection. The roller is inserted to 
lessen the friction by rolling instead of rubbing. The 
vaive stem extends upward into the valve chamber, 
and is encircled by the coiled spring e; the stem is 
guided by the guide at g. The exhaust is at E; I 
is the pipe leading from the vaporizer V to the inlet 
port in the valve chest. The inlet valve is directly 
below the spring S and is inverted, being held in 
place by the spring. The dome-shaped cap con- 
taining the inlet valve is removable for access to 
both valves. The complete cover is also removable. 
It will be observed that this engine has an open 
frame very similar to that of a steam engine, giving 
free access to the crank-pin and main bearings; the 
latter are shown fitted with oil boxes h instead of 
the grease cups, as there is no pressure tending to 
force the oil out along the shaft as in the two-cycle 
type. This open base not only makes the bearings 
more accessible, but renders it easier to lubricate 
them and keep them cool. At H is the ignition 
gear. P is the cooling water pump, run by the ec- 
centric e. The suction is piped to d and the pump 
discharges through the pipe k into the cylinder. 
The outlet for the cooling water is at 0; N is the 



396 MECHANICS 

cylinder oil cup for oiling the bore of the cylinder. 
The compression cock R is for relieving the com- 
pression at starting. The coupling at X is for 
attaching the propeller shaft. 

In this engine, the cylinder, base and bolting 
flange are one casting, the upper half of the main 
bearing being removable for the insertion of the 
shaft. The cover is bolted on separately. 

AUTOMOBILE FRAMES 

The chassis for the single-cylinder, eight horse- 
power motor machine shown herewith is built on the 
principle of most frames, of any make and is typical 
of the majority of light motor car chassis at present 
in use. 

A diagrammatic plan of the eight horse-power, 
single-cylinder chassis is shown in the accompanying 
illustration (Fig. 226) in which, A indicates parts 
enclosed, taking the mixture of gasolene and air from 
the float-feed spray carburetor B, which has an 
automatic air regulator. The purpose of this last 
device is to dilute the mixture when the engine has 
a light load and is inclined to race; generally speak- 
ing, this regulator serves to proportion the ingred- 
ients of the explosive mixture to the requirements 
of the engine. Current O for the ignition of the 



ir P" Tf 



r^ 



m 




S 



^Tia 



CD 



1 



^ 



r^ 




9i 



P^ 



i 

■i 



398 MECHANICS 

explosive mixture (ignition occurs once for every two 
revolutions of the fly-wheel), is supplied by an ac- 
cumulator and intensified by a high-tension coil. 
The products of combustion pass through the 
exhaust pipe C to the muffler D, from which they 
pass to the atmosphere through a series of fine holes. 
The starting handle E makes a simple connection 
with the end of the motor shaft F when required. 
G is the fly-wheel. The drive from the engine is 
through a universal joint H to the change-speed 
gear J, the latter consisting of two trains of toothed 
wheels, a big wheel on the primary shaft gearing 
with a small one on the secondary shaft to give a 
high speed, and vice versa. From the change-speed 
gear, the drive is through a shaft K, having a uni- 
versal joint L at each end, to the bevel gearing 
above the differential gear of the live rear axle. 
Bevel gears and the differential gear are all contained 
in the casings M. Three brakes are fitted, one oper- 
ated by pedal, working on a drum N secured to 
the propeller shaft, the others operated by the side 
lever and working on drums O O, secured to the rear 
wheels. The change-speed gear gives three speeds 
forward and a reverse; the frame is of pressed steel; 
the rod and wheels are of the artillery type and carry 
700 mm. by 85 mm. pneumatic tires. The gasolene 




<V 

til 

'A 



400 MECHANICS 

tank holds 43^2 gallons, sufficient for 200 miles, and 
the lubricating oil tank holds 1 gallon, sufiicient for 
350 miles. Any beginner in motoring matters, who 
studies the diagram, will obtain a fair idea of the 
mechanism of the customary type of light car chassis. 

A chassis, suitable for a l}/^ horse-power quick- 
speed, two-cylinder motor, is shown in Fig. 227. 

It is not necessary to enter fully into the details 
of construction after describing such a typical gear- 
driven car as that at Fig. 226. 

The frame A is of tubular steel, there are four 
semi-elliptic springs, and the artillery wheels have 
28-inch by 3-inch tires. The two-cylinder engine 
B is one casting, with a large waterway covered by 
an inspection plate C. The bore is 3.5 inches stroke 
4-inches, cylinder capacity 76.9 cubic inches, and 
the piston displacement is 92.300 cubic inches per 
minute. A governor automatically throttles the in- 
let when the motor attempts to race, but by means 
of a lever the governor can be cut out and the motor 
accelerated from its normal speed of 1,200 revolu- 
tions per minute. The balanced crank has but a 
single throw; the water circulation is assured by a 
motor-driven pump, and there is a belt-driven fan 
behind the radiator. The commutator is easily 
accessible, being mounted on a bevel shaft lying in 



1 



MOTORS AND TYPE -WRITERS 401 

a sloping position and passing through the side of the 
crank chamber. Ignition is high tension with wide 
contact, the wiring being enclosed in a neat wooden 
casing. The change-speed gear D gives three speeds 
and a reverse, and its main bearings are fitted with 
ring lubricators. A pressure sight feed lubricator on 
the dash-board has three outlets, one to the engine, 
another to the main clutch, and a third to the driving 
pinion on the end of the propeller shaft. The brakes 
are of the usual kind. In Fig. 2, E is the carburetor, 
F the inlet and G the exhaust pipes, H the exhaust 
muffler, J the brake pedal, K the clutch pedal, L the 
band-brake on the propeller shaft, and M the inter- 
nal expanding brakes on the wheel hubs. A shield is 
arranged under the front of the car to protect the me- 
chanism from mud and dust. The weight of the car 
unladen is about 1,414 pounds, the wheel base is 733/^ 
inches, the track 46 inches, and the over-all dimen- 
sions are 111 inches by 60 inches. During a 600-mile 
trial this engine consumed 36 gallons, 6 pints of gas- 
olene, this being at the rate of 1 gallon for every 16.9 
car miles; .077 gallon was consumed every ten miles. 

THE MODERN TYPE-WRITER 

Every home of importance contains a writing 
machine of some kind, and these often require some 



402 MECHANICS 

little adjustment or ''fixing." It is within the 
capacity of any bright boy to make these adjustments, 
or to do the little fixings, if he tries it earnestly. 

The first marketable type-writer was introduced in 
the year 1875. No sooner had the type-writer ac- 
quired a commercial value, than the fire of inventive 
talent was awakened in Europe and America, and 
type-writer after type-writer appeared on the mar- 
ket — a few came to stay, but the many disappeared, 
either during the chrysalis or experimental stage, 
or shortly after it had been passed. Inventors and 
investors have learned that hasty innovations and 
untried experiments spell ''failure" in the type- 
writer field, and only patient and careful study, 
backed by experience, tireless elffort, and abundant 
resource, have a chance of success. 

By the year 1888, there were six different kinds of 
machines in the market, to-day there are at least 
twenty, but the favourites seem to be, "The Rem- 
ington," "Smith Premier," "The Underwood" and 
"The Oliver." 

Modern type-writers may be defined as being 
tabulating, book recording, card indexing, and 
document writing machines. They are speedier 
and produce finer and more varied work than their 
predecessors. 



MOTORS AND TYPE -WRITERS 403 

The manner in which the type-writer performs 
its work is of the simplest. The type-writer may be 
considered as composed of three general parts, as 
follows: 

The keyboard, by which the operation of the 
machine is directed. 

The type mechanism, by which the desired letters 
are, one after the other, in any desired sequence, 
imprinted on the paper. 

The carriage, which holds the paper in proper 
position for writing, and which, by its regular move- 
ments, provides for the spacing of letters and lineg. 

The Remington may be considered the pioneer 
of writing machines. In appearance the Remington 
No. 5 (introduced in 1888) is square, and strikes a 
novice as being somewhat complicated. It is only 
the multiplicity of parts, however, which creates 
this impression. The machine is not complex, the 
same parts being repeated over and over again. 
The action is simplicity itself. The machine is 
quite open on every side, so that its entire construc- 
tion can easily be seen. There is a japanned iron 
frame enclosing and holding the working parts, 
consisting of a base, four upright posts, and a top 
plate. In front is a series of keys arranged in four 
banks, like the keys of an organ, each key represent- 



404 MECHANICS 

ing the two characters, termed "upper" and "lower" 
case letters. These are connected with long light 
wooden levers, which, being depressed, communicate 
motion by means of a rod fastened to the lever of 
a type bar. At the end of each type bar is fixed the 
hard metal type representing the two characters. 
The type bars are arranged in a circle, therefore 
the point of percussion of the type on the paper is at 
a common centre. The inking is done by a ribbon, 
which travels automatically across the machine, 
winding and rewinding on and from spools. 

The paper is inserted between two rollers; one of 
rubber, called the "paper cylinder," and the other 
of wood, called the "feed roll." The rollers are 
held together by two elastic india-rubber bands. 
As one revolves so does the other. The portion 
which holds these rollers is designated the "car- 
riage." By a clever, yet simple piece of mechanism, 
this carriage is caused to travel, simultaneously 
with the return of the type or spacing bar, from right 
to left, the width of a letter at each movement across 
the machine. The carriage works on a sliding frame, 
and this sliding mechanism is controlled by two 
keys, which do not impress letters on the paper. 
These change the character of the printing keys, 
causing them to print capitals or small letters. 



MOTORS AND TYPE -WRITERS 405 

numerals or other marks at will. Depress the key 
marked *' upper case" and all the keys will print 
capitals; remove the finger and they all print small 
letters again. Moreover, the machine can be ar- 
ranged to print capitals continuously by the mere 
raising of a lever, and quite independently of the 
"upper case" shift key. 

To obtain an impression, the required key is 
struck lightly, and the type bar causes the type to 
strike against the ribbon, thus leaving an imprint 
on the paper held round the cylinder; the carriage 
moves automatically the width of the letter, and the 
operation is repeated until a word is completed. 
Then the "spacing bar" at the front of the machine 
is depressed at any point, thereby securing the requi- 
site space between the words. 

When the end of a line is reached, warning is 
given by the ringing of a bell, and then, by pulling 
out the lever at the right-hand side of the carriage 
and gently pressing to the right, the paper carriage 
is advanced into position to receive the next line. 
The distance between the lines and the width of the 
writing can be regulated. The paper carriage being 
hinged at the back allows of its being raised from the 
front by the hand, so that the line that has just been 
written can be inspected. 



406 MECHANICS 

The motive power is imparted by an adjustable 
coiled spring, a thin leather strap being fastened 
to it and the carriage, and the uniform space is 
governed by two clutches working on a rack. This 
rack is fixed on a rocking shaft, and derives a swing- 
ing motion from a universal bar fixed beneath the 
light wooden key levers. 

A small lever attached to the left of the carriage 
holds its movements under the control of the oper- 
ator. Two scales are fixed on the machine, and these 
in conjunction with the pointer, permit of head- 
lines being centred, corrections made, etc. 

In some machines, a special key and its accom- 
panying mechanism is provided for each character 
or sign used — such are termed "complete" key- 
board machines. In others, each key is made to 
represent the letters or signs — such are designated 
"single-shift" machines. Others, again, have two 
shift-keys, and each key represents not only a lower 
case (small) and an upper case (capital) letter, but 
a figure or other sign as well — such are known as 
"double-shift" machines. 

The two classes of modern type-writers may be 
arranged into three groups, namely: 

"Blind" writers, in which the writing remains 
hidden until exposed by manipulative effort of the 



MOTORS AND TYPE -WRITERS 407 

operator. " Semi -visible " writers, which show only 
the last lines, or only expose the centre of the paper, 
hiding the writing at both ends of the line. ''Vis- 
ible" writers, which expose a character directly in 
front of the operator the instant it is imprinted; 
the character subsequently does not pass out of 
sight, by feeding behind a scale or bar, or other ob- 
struction. This classification and grouping is for 




Fig. 228. Remington type- writer No. 7 

convenience only, and is in no way intended to 
denote superiority. 

With regard to the Remington, many changes of 



408 MECHANICS 

the details of construction, tending toward strength, 
durability, and a greater ease and convenience of 
operations, have been introduced into the machine, 
which have survived the severe test of time. This is 
especially the case with Remington No.7(see Fig. 228). 
The most important of these valuable improvements 
are: An entirely new form of escapement, giving 
increased speed and an easy touch. The carriage is 
stronger and lighter, and steadier in all respects. 
The annoying rubber bands, which guide the paper 
around the platen have been discarded for a new form 
of paper guide, which may be adjusted to any de- 
sired point. The paper feed has been so arranged as 
to render it possible to write on wide or narrow paper, 
and this can be fed into the machine by a simple 
movement of the hand without lifting the carriage, 
and can be turned forward or backward at will. 
The ribbon movement is improved and works en- 
tirely automatically, reversing and giving a lateral 
movement. The marginal stops also are improved, 
and simple means provided for writing outside the 
margin whenever desired. There is a keyboard lock, 
locking the types at the end of the line, and thus pre- 
venting one letter being printed over another. A 
new variable line spacer is embodied, which makes 
it easier to write at any point on the paper, and 



MOTORS AND TYPE - WRITERS 409 

prolongs the life of the platen for the reason that 
the type no longer strikes in unchanging grooves. 
An adjustable side guide for arranging the paper 
to any desired marginal indentation is a recent ad- 
dition. A new two colour ribbon lever bearing a 
disc, which signals the color which the machine is 
adjusted to write is another recent addition. 

The Smith-Premier type (Fig. 229) has six models 




Fig. 229. Smith Premier No. 4 

in the market and all nearly alikein their mechanism, 
differing only in the carriage arrangements, or the 
number of the characters. The machine is par- 
ticularly simple in construction, and claims, by 
means of a very long and strong adjustable bear- 
ing, to have secured a perfect and permanent align- 
ment. The type bars work on hardened steel 



410 MECHANICS 

bearings, 1^ inches apart, and the type bars are 
the shortest of any on a ''complete" keyboard 
machine. But the original and exclusive feature 
of the machine is the rocking shaft, which replaces 
the usual wooden or metal key lever. This con- 
sists of a circular rod, passing from the front to the 
rear of the machine — one rod for each key. Pro- 
jecting from each shaft is a small bar, which is 
attached at the front end to the lower portion of the 
key stem. A similar projection is attached to the 
rod communicating with the type bar, and the re- 
sult is that on the depression of the key the rocking 
shaft is made to revolve slightly, and so raise the 
free end of the type bar to the printing point. The 
type bar hangers are solidly riveted to the type 
ring. It will be seen that matters are so arranged 
that the amount of force to imprint the character 
is precisely the same in every case — a uniform, light 
and elastic touch. A very noticeable feature is 
its quietness in operation, due to the rigidity of its 
parts, and the fact that the ball-bearing principle 
is adopted wherever it can be used to advantage. 
It is also equipped with a circular brush, built into 
the machine, into which, a handle can be immedi- 
ately inserted, when, with a turn or two, the whole 
of the type can be cleaned. 



MOTORS AND TYPE -WRITERS 411 

The most striking recent development is the adop- 
tion of a three-coloured ribbon device. A simple 
movement of the lever in front of the machine 
brings the required colour into place ready for use. A 
two-colour or single colour ribbon may be employed. 
If desired. The ribbon can be instantly shifted 
from the printing point for duplicating purposes. 
The ribbon reverses automatically, and it is at- 




Fig. £30. The Oliver No. S 

tached to the spools with clamps — one on each 
spool, dispensing entirely with pins and tapes. 



412 MECHANICS 

The Oliver, Fig. 230, difiFers in mechanical principle 
from other machines. It has a wide U-shaped steel 
type bar, provided with a tool-steel axle as broad 
as the bar is long, and braced joints insuring the 
alignment without guides. The connection between 
the type bars and the key levers is direct and per- 
pendicular. The type bars strike down on the 
platen in a line perpendicular to its plane, thus trans- 
mitting the maximum power with the minimum 
resistance, and further, maintaining the alignment 
with several sheets as with one. The type are of 
steel, and lie face upward — very convenient for 
cleaning. The keyboard is the "Universal," hav- 
ing twenty -eight keys with a *' double" shift, giving 
eighty-four characters and the special model thirty- 
two keys, giving ninety-six characters. 

The tension and depression of the keys are light 
and uniform. It may also be noted that the type 
blocks decrease in weight with the increase of length 
of type bar — necessary to secure a uniform stroke. 
The escapement mechanism is exceedingly simple 
and positive, and although very rapid is almost 
frictionless. The writing is semi-visible. The car- 
riage is provided with three paper-feed rolls, thus 
ensuring a perfect feed of the paper down to the 
bottom edge of the sheet. It runs on anti-friction 



MOTORS AND TYPE -WRITERS 413 

travellers on guide rails, ensuring an easy and steady 
motion. It is equipped with all the necessary 
devices. The line space mechanism operates auto- 
matically as the carriage is returned from the 
left to the right for a new line. The machine 
is compact and portable — weight about twenty 
pounds. 

The parts of any of the machines now in the mar- 
ket, may readily be disconnected, but care must be 
taken by the novice in laying aside the parts so that 
they may be easily and correctly assembled. Re- 
pairs on the various parts may be made while out, 
and when made may be placed in situ. Any or all 
of the parts may be cleaned when the carriage is 
taken off. A little study of the machine when 
sitting before a person, will enable him to under- 
stand its mechanism, and when this is accomplished, 
cleaning and repairing can be done intelligently. 

The tendency of the times is to employ the type- 
writer whenever possible. Special devices are from 
time to time invented to meet extended uses. The 
most important of recent applications is to office 
work for billing and book-keeping; this work alone 
has necessitated important modifications. In this 
direction, the tabulator calls for review. The lack 
of a practical method enabling tabular matter to 



414 MECHANICS 

be typed with a rapidity equal to that of the or- 
dinary typing has long been felt to be a deficiency 
in type-writers. The invention of the tabulator has 
enormously increased the scope of the machine in 
this direction. 

The tabulator is a device by means of which, 
figures or words can be written in columns, with 
out employment of the space bar or carriage re- 
lease lever, or any adjustment whatever of the car- 
riage by hand. By its use, the carriage may be set 
automatically at any point that may be required. 
At present this device is an accessory to most ma- 
chines, but in the near future, it must form an in- 
tegral part of all machines, and further, enable the 
carriage to be automatically placed in a proper 
position to write numbers in correct relation to 
each other in columns; that is, units under units, 
tens under tens, and so on. The built-in tabulators 
of to-day, with but two exceptions, are deficient in 
this respect. The tabulator in either form does 
not interfere with the use of the machine for other 
work, such as correspondence, etc. 

The tabulator was followed by the introduction 
of a bi-chrome (two-coloured ribbon), and quite re- 
cently the Smith Premier Typewriter Company 
has advanced still further in this direction by in- 



MOTORS AND TYPE-WRITERS 415 

troducing a tri-chrome (three-colour) ribbon. By a 
simple movement it is possible to vary the colour 
of the impression instantaneously, so that credits, 
marginal notes, footnotes, and underscoring may 
be indicated in red or other colour preferred. One- 
colour ribbons can be used if desired. 

The machine embodying the parti-coloured ribbons 
and tabulator devices are generally known as '*in- 
voicing" machines, and by simple arrangements, 
every phase — not only of correspondence, but also 
of office and statistical work — can be accomplished, 
with an enormous saving of time. Items can be 
made on sheets, which may be taken from the 
machine with absolute certainty that when re-in- 
serted, the subsequent entries will fall into their 
proper places. 

Card Indexing, — For greater convenience in card 
indexing, special platens are obtainable, or the or- 
dinary platens can be temporarily fitted with a 
metal clip. Both can be fitted to or removed from 
the machine in a few seconds, and the cards can be 
adjusted in an instant. The increasing use of the 
card file system for a wide variety of purposes lends 
special importance to the value of the type-writer 
for this class of work. 

Interchangeable Carriages, — ^For years the thou- 



416 MECHANICS 

sand and one wide forms, statements, and blanks 
common in every business oflSce, have been filled 
by the pen, the reason being that there was no 
machine practicable for both wide and ordinary 
work. The manufacturers of most of the modern 
type-writers now have models embodying inter- 




Fig. 231. Interchangeable carriage 

changeable carriages, which enable any one possess- 
ing a machine with this improvement to have at 
the same time a set of carriages from the largest to 
the smallest, all of which can be used upon one 
machine. In one or two makes this is additional 
to interchangeable platens. 

Duplicators. — The value of a mechanical con- 
trivance for the rapid and effective multiplication 
of copies of documents is fully recognized at the 
present time. 

Duplicating machines have been on the market for 
several years. They will produce from one type- 



MOTORS AND TYPE-WRITERS 417 

script original up to 3,000 copies, of any size, from a 
post card to a sheet of brief, every copy having the 
exact appearance of an original. While there are 
various makes and styles of duplicators, the main 
principle is the same throughout. The original is 
prepared by the now well-known stencil process; that 
is, writing the matter required with a type-writer 
on a sheet of waxed paper. The pressure of the type 
expels the wax out of the paper and leaves openings 
through which the ink can penetrate. In the Roneo 
rotary duplicator, a metal frame supports a cylinder 
of thin, perforated steel. On the outer surface of 
the cylinder is stretched a linen ink-pad, and over 
this is placed the stencil. The pad is inked by a 
rubber roller resting in an ink receptacle suspended 
between the two sides of the framework. By 
means of a simple lever this roller can be brought into 
contact with the cylinder, and ink is thus supplied 
as required. The cylinder is rotated by a handle. 
Paper fed into the machine is gripped by a rubber 
impression roller, which presses it against the stencil 
as the cylinder revolves, and the sheet perfectly 
printed, is then automatically discharged on the 
other side. The rotary can be fitted with three 
devices, namely, a simple contrivance, which auto- 
matically feeds the sheet into the machine, reducing 



418 MECHANICS 

hand labour to a minimum; an interlever, which 
automatically drops an interleaving sheet as each 
copy is printed — thus permitting of the use of 
highly glazed or very hard paper; a cyclometer for 
registering the number of copies. The rotary sys- 
tem is far superior to the hand duplicators in the 
matter of speed ; such a machine will print ten copies 
while the hand device prints one. There is no lost 
motion, a copy being printed and discharged at 
every revolution. 

Press Copying. — ^At the present time, there are 
four methods of letter copying in vogue, namely: 
(1) The letter-book method, damping sheets and 
screw press. (2) Roller process, water bath and 
drying drum. (3) Carbon paper. (4) The chem- 
ical letter copier. 

The roller copies employ a water bath, and give 
but little if any improvement in the regulation of 
the degree of moisture. The copies are wound on 
a drying drum to prevent off -setting, and subse- 
quently have to be cut apart for filing purposes. 

The carbon process enables the answers to be 
filed with the original letter. 

The modern chemical letter copier offers distinct 
advantages over other methods. It consists of a 
simple machine designed to carry a roll of specially 



MOTORS AND TYPE -WRITERS 419 

prepared paper. The letter to be copied is laid on 
the feed board, the handle is turned, the sheet is 
fed automatically into the machine. 

It will be noticed that a water bath and brush or 
damping sheets, are completely dispensed with; 
there is no " oflF-sheeting " and no drying drum. 
The copy may be either filed with the letter to which 
it relates, or placed, day by day, in a cover having 
the appearance of an ordinary letter-book; or two 
copies can be made of each letter — one for filing 
and the other for the book. 

(1). A type-writer should be durable. Every 
part should be simple and strong and adapted to 
serve its purpose with the smallest degree of wear. 
Every mechanical movement must be definite, 
and incapable of incomplete performance. All 
wearing parts should be adjustable and inter- 
changeable. 

(2). It should possess absolutely "visible" writ- 
ing. The common-sense way to write easily and 
speedily is to see what you are writing while you are 
writing it. 

The writing should be performed in such a part 
of the machine as to be most readily seen during 
progress. 

(3). The keyboard — on type bar machines in 



420 MECHANICS 

particular — should be that known as the "Uni- 
versal," or "Standard" arrangement. 

The keys on any style of keyboard should have a 
light and uniform depression, so that the machine 
may be operated with the minimum of fatigue. 

(4). The types should present an even and reg- 
ular appearance, termed " alignment. " A type bar 
made of suitable material in the right way is the 
keystone of typewriter construction. In all ma- 
chinery, there is some part on which falls the greatest 
strain and wear; consequently on the durability 
of that part rests the life of the machine. The 
devices used to secure alignment are numerous and 
ingenious. One machine depends on a wide pivoted 
bearing and a rigid type bar; another has a bearing 
composed of a continuous steel rod, with a type 
bar flexible while in motion, and made rigid at the 
printing point by means of guides; a third employs 
a wide pivotal bearing, a flexible type bar and an 
indispensable guide plate at the printing point; a 
fourth employs a compound type bar and an indis- 
pensable guide at the printing centre, and so on. 
Some have wide and adjustable bearings, to enable 
the wear to be taken up. These devices, however, 
are not the only essentials; The type bar hangers 
in machines embodying the pivotal principle need 



MOTORS AND TYPE -WRITERS 421 

to be rigid and solidly fixed, while the paper carriage 
should be perfectly rigid and present a level and 
even platen surface for the type to strike against. 

(5). The type should be capable of being easily 
and quickly cleaned, and in such a way as not to 
injure the type or soil the hands. A device should 
be embodied for rendering it impossible to batter 
the face of the type when the type bars are acci- 
dentally struck one against the other, and for pre- 
venting the type perforating or puncturing the 
platen. 

(6). The mechanism controlling the movement 
of the carriage should act rapidly and uniformly, 
and its tension should be adjustable. The carriage 
should have a sure and regular paper feed and be 
capable of accommodating any smaller width of 
paper; also the margin regulators and bell trip 
should be easily and readily altered. 

(7). The platen roll should be instantly inter- 
changeable, thereby allowing of a soft substance 
platen being used for a single copy work and a hard 
one for manifolding. If the hard platen is of re- 
duced diameter, more perfect alignment is secured 
on machines employing a complete circle of rigid 
type bars and a central top carriage. 

(8). The line-spacing mechanism should be var- 



422 MECHANICS 

iable, and effected by one movement at all times; 
that is, the same movement that accomplishes the 
line feed should be utilized to return the carriage 
for a new line. 

(9). The ribbon movement should consist of a 
reliable feeding mechanism, and allow of the fabric 
being quickly withdrawn, replaced, or adjusted. It 
should bring the whole surface in contact with the^type, 
and also automatically reverse the endwise travel. 

(10). The machine should be as noiseless in 
operation as possible. Machines diflfer very much 
in this particular. The employment of the guides 
to force the alignment introduces metallic contact, 
and consequent friction and noise. 

COPYRIGHTS 

Directions for Securing Copyrights, under the revised 
act of Congress, which took effect August 1,1874- 

(1). A printed copy of the title of the book, 
map, chart, dramatic or musical composition, en- 
graving, cut, print, photograph, or a description 
of the painting, drawing, chromo, statue, statuary, 
or model or design for a work of the fine arts, for 
which copyright is desired, must be sent by mail 
or otherwise, prepaid, addressed: Librarian of 
Congress, Washington, D. C. 



MOTORS AND TYPE-WRITERS 423 

This must be done before publication of the book 
or other article. No entry can be made of a written 
title. 

(2). A fee of fifty cents, for recording the title 
of each book or other article, must be enclosed with 
the title as above, and fifty cents in addition (or 
one dollar in all), for each certificate of copyright 
under seal of the Librarian of Congress, which will 
be transmitted by early mail. 

(3). Within ten days after publication of each 
book or other article, two complete copies of the 
best edition issued must be sent, to perfect the 
copyright, with the address Librarian of Congress, 
Washington, D. C. 

The postage must be prepaid, or else the publi- 
cation enclosed in parcels covered by printed Penalty 
Labels, furnished by the Librarian, in which ease 
they will come free by mail, according to rulings 
of the Post-office Department. Without the de- 
posit of copies above required the copyright is void, 
and a penalty of $25 is incurred. No copy is re- 
quired to be deposited elsewhere. 

(4). No copyright is valid unless notice is given 
by inserting in every copy published, on the title 
page or the page following, if it be a book; or if a 
map, chart, musical composition, print, cut, en- 



424 MECHANICS 

graving, photograph, painting, drawing, chromo, 
statue, statuary, or model or design intended to be 
perfected as a work of the fine arts, by inscribing 
upon some portion thereof, or on the substance 
on which the same is mounted, the following words, 
viz: "Entered according to act of Congress, in the 
year by , in the office of the Libra- 

rian of Congress, at Washington," or, at the option 
of the person entering the copyright, the words: 
"Copyright, 19 , by 

The law imposes a penalty of $100 upon any per- 
son, who has not obtained copyright, who shall 
insert the notice "Entered according to act of 
Congress," or "Copyright," etc., or words of the 
same import, in or upon any book or other article. 

(5). Any author may reserve the right to trans- 
late or to dramatize his own work. In this case, 
notice should be given by printing the words "Right 
of translation reserved," or "All rights reserved," 
below the notice of copyright entry, and notifying 
the Librarian of Congress of such reservation, to be 
entered upon the record. 

(6). Each copyright secures the exclusive right 
of publishing the book or article entered for the 
term of twenty-eight years. Within six months 
before the end of that time, the author or designer, 



MOTORS AND TYPE-WRITERS 425 

or his widow or children, may secure a renewal for 
the further term of fourteen years, making forty -two 
years in all. Application for renewal must be ac- 
companied by explicit statement of ownership, in 
the case of the author, or of relationship, in the case 
of heirs, and must state definitely the date and place 
of entry of the original copyright. 

(7). The time within which any work entered 
for copyright may be issued from the press is not 
limited by any law or regulation, but depends upon 
the discretion of the proprietor. A copyright may 
be secured for a projected work as well as for a 
completed one. 

(8). A copyright is assignable in law by any in- 
strument of writing, but such assignment must be 
recorded in the office of the Librarian of Congress 
within sixty days from its date. The fee for this 
record and certificate is one dollar, and for a certified 
copy of any record of assignment one dollar. 

(9) . A copy of the record (or duplicate certif- 
icate) of any copyright entry will be furnished, under 
seal, at the rate of fifty cents each. 

(10) . In the case of books published in more than 
one volume, or of periodicals published in numbers, 
or of engravings, photographs, or other articles 
published with variations, a copyright is to be en- 



II I 



426 MECHANICS 

tered for each volume or part of a book, or number of 
periodical, or variety, as to style, title, or inscrip- 
tion, of any other article. 

(11). To secure a copyright for a painting, statue, 
or model or design intended to be perfected as a 
work of fine arts, so as to prevent infringement by 
copying, engraving, or vending such design, a 
definite description must accompany the application 
for copyright, and a photograph of the same, at 
least as large as ''cabinet size," should be mailed 
to the Librarian of Congress within ten days from 
the completion of the work or design. 

(12). Copyrights cannot be granted upon Trade- 
marks, nor upon Labels intended to be used with any 
article of manufacture. If protection for such 
prints or labels is desired, application must be made 
to the Patent OflSce, where they are registered at 
a fee of $6 for labels and $25 for trade-marks. 

(13). Every applicant for a copyright must state 
distinctly the name and residence of the claimant, 
and whether the right is claimed as author, designer, 
or proprietor. No affidavit or formal application 
is required. 

Office of the Librarian of Congress. 



29 W 



JUL 8 l^n 












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